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Engine swap/replacement on my 1998 VFR800 (bad engine, curious on any tips and tricks)


VicSev93

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Hello all!

 

I hope everyone is doing well, and enjoying their VFR's, I wish I could be doing the same, but sadly, I cant. About a month ago I bought a 1 owner, 15k mile VFR, from 1998. Anyway, After getting it seen by mechanics (the bike randomly died/turned off) and having the compression tested multiple times, I have been told the piston rings are bad, one of the cylinders is showing a reading of 60, while the other 120 (the two front ones) the two rear ones are at around 148 each. I was given two options, either a top end rebuild, ordering new piston rings (and maybe pistons themselves, but I could not for the life of me find anything for the bike online parts wise? if you guys have any links or info, please share) or the second option, was to engine swap. I found some engines on eBay, and one in parotcualr looked very good to me, however, it is from a year 2000. Would there be any issues trying to shove it into a 1998? 

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It's very unlikely that a 15k mile 5th gen would have bad piston rings unless the previous owner never checked the oil.

Typically if a 5th is dieing, its because the charging system has gone South. I would get a 2nd opinion with someone you

TRUST.......

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23 hours ago, mello dude said:

It's very unlikely that a 15k mile 5th gen would have bad piston rings unless the previous owner never checked the oil.

Typically if a 5th is dieing, its because the charging system has gone South. I would get a 2nd opinion with someone you

TRUST.......

Hello!, the person is someone I trust dearly, one of my best friends.  I just needs the parts. The charging system has also been checked. I just need to know where I can get the parts I need, or if a 2000 vfr engine will fit. Please let me know🙂

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^^^ I agree with mello dude - it's highly unlikely that a 15,000 mile engine would have those issues unless run without oil, overheated or otherwise severley abused. 

 

Regardless, to your question - the only difference you would notice between the '98 and '00 engines would be the water neck on the left side of the head and the thermostat housing.  Each has an extra (compared to your '98) outlet that leads to the wax unit '00 model has vs your '99 which does not (hence the fast idle lever on you left switch pod).  You'll want to swap the '98 pieces over to the '00 motor (so you'll need o-rings).  Other than that, it's a plug and play swap.  Heck, those motors even bolt directly in to a 6th gen - so no worries at all on yours.  You will need to devise a way to support the rear of the bike while the motor is out - an overhead attach point, a couple of ladders with a beam, or as some have done, leave the engine on a floor jack, and lift the frame off the motor and move it off like a wheel barrow on the front wheel.  Regardless, it's long and tedious, but very doable. 

 

In the diagram, the outlets on the '00's wax unit coolant outlets are circled in red.  Your '99 does not have those.  The fittings are otherwise identical and interchangeable.  You'll want a new O-ring (#16).  While you're in there, it would be good to change out any suspect hoses, install a new thermostat as well as replace the #18 O-rings.  Mine were fossilized after fending off coolant for 2 decades. 

image.png

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3 minutes ago, Cogswell said:

^^^ I agree with mello dude - it's highly unlikely that a 15,000 engine would have those issues unless run without oil. 

 

Regardless, to your question - the only difference you would notice between the '98 and '00 engines would be the water neck on the left side of the head and the thermostat housing.  Each has an extra (compared to your '98) outlet that leads to the wax unit '00 model have vs your '99 which does not (hence the fast idle lever on you left switch pod).  You'll want to swap the '98 pieces over to the '00 motor (so you'll need o-rings).  Other than that, it's a plug and play swap.  Heck, those motors even bolt directly in to a 6th gen - so no worries at all on yours.  You will need to devise a way to support the rear of the bike while the motor is out - an overhead attach point, a couple of ladders with a beam, or as some have done, leave the engine on a floor jack, and lift the frame off the motor and move it off like a wheel barrow on the front wheel.  Regardless, it's long and tedious, but very doable. 

 

In the diagram, the outlets on the '00's wax unit coolant outlets are circled in red.  Your '99 does not have those.  The fittings are otherwise identical and interchangeable.  You'll want a new O-ring (#16).  While you're in there, it would be good to change out any suspect hoses, install a new thermostat as well as replace the #18 O-rings.  Mine were fossilized after fending off coolant for 2 decades. 

image.png

Thank you so much! Everyone on here is so helpful, I GREATLY appreciate it!

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Now that I think about it, while you're doing that you'd have the throttle body off (you'll want to use you '98 TB - it differs from the '00 unit) - there would be no better time to remove the injectors and send them out for a cleaning.   Also, the valves will never be easier to check than while the engine is sitting on the bench / floor / pallet - whatever - it's right in front of you.  Just pull the cam covers and go through the procedure with your feeler gauges.  Once you button it all back up, you'll know you've got the most difficult to get at maintenance items done and you're good to go for a long time.    :fing02:

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Follow-up leakdown test would pinpoint where leak is.

Did you do cam-timing and valve-clearance check? 

Be sure to get compression # from eBay engine with guarantee. I got engine once and couldn’t figure out why it wan’t running. Turned over smoothly by hands. Had fuel & spark. Cam timing and valve clearances were spot-on. Did compression-test and it was 0-psi across board! Took it apart and it was missing pistons & rods!!  

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1 hour ago, VicSev93 said:

Hello all!

 

I hope everyone is doing well, and enjoying their VFR's, I wish I could be doing the same, but sadly, I cant. About a month ago I bought a 1 owner, 15k mile VFR, from 1998. Anyway, After getting it seen by mechanics (the bike randomly died/turned off) and having the compression tested multiple times, I have been told the piston rings are bad, one of the cylinders is showing a reading of 60, while the other 120 (the two front ones) the two rear ones are at around 148 each. I was given two options, either a top end rebuild, ordering new piston rings (and maybe pistons themselves, but I could not for the life of me find anything for the bike online parts wise? if you guys have any links or info, please share) or the second option, was to engine swap. I found some engines on eBay, and one in parotcualr looked very good to me, however, it is from a year 2000. Would there be any issues trying to shove it into a 1998? 

If you go the top end route.. Partzilla has pistons/rings .25 over.... 

https://www.partzilla.com/catalog/honda/motorcycle/1999/vfr800fi-a-interceptor/crankshaft

 

Its a tough choice, engine swap or top end rebuild..... What does the oil in the engine look like? Guinness Stout or Truth IPA?

 

16 minutes ago, squirrelman said:

u need to discover what is responsible for low compression, rings or valves.

 

Squirrel is right it could be a valve issue...... 

 

 

 

Totally wish you the best! :beer:

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I'd dig in to it a little more and verify compression like squirrelman says.

 

Although...it can be a little bit of a chance buying a used motor but you can get the compression checked before or after you buy. I dropped a used $300 20K mile motor from a wrecker in mine and have put 25K trouble free miles on it. I understand the rebuild it urge, but these motors are (typically) almost bullet-proof. Spend the saved money on injector cleaning, new hoses, gaskets...

 

IMG_0062.JPG

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2 minutes ago, vfrcapn said:

I'd dig in to it a little more and verify compression like squirrelman says.

 

Although...it can be a little bit of a chance buying a used motor but you can get the compression checked before or after you buy. I dropped a used $300 20K mile motor from a wrecker in mine and have put 25K trouble free miles on it. I understand the rebuild it urge, but these motors are (typically) almost bullet-proof. Spend the saved money on injector cleaning, new hoses, gaskets...

 

IMG_0062.JPG

 

Hello all! Once again, thank you all for the replies, let me go over what has been done to the bike so far, the injectors have been replaced, the fuel rails have been cleaned, the water pump (which was clogged) was cleaned, and fuel pump gasket replaced, the spark plugs were also replaced, with all basic maintenance done, we did to the valves aswell, checked it with feeler gauges, and all 4 were pretty off, however, everything was fixed. Even with basic maintenance and the valves done, the bike still showed the same characteristics. it would shut off randomly, and it would also not rev above 2k rpm (I honestly dont know why, any thoughts on this?) as I have mentioned before, the compression was tested many times, and the front two cyl were at 60 and 120. 😞

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Just now, VicSev93 said:

 

Hello all! Once again, thank you all for the replies, let me go over what has been done to the bike so far, the injectors have been replaced, the fuel rails have been cleaned, the water pump (which was clogged) was cleaned, and fuel pump gasket replaced, the spark plugs were also replaced, with all basic maintenance done, we did to the valves aswell, checked it with feeler gauges, and all 4 were pretty off, however, everything was fixed. Even with basic maintenance and the valves done, the bike still showed the same characteristics. it would shut off randomly, and it would also not rev above 2k rpm (I honestly dont know why, any thoughts on this?) as I have mentioned before, the compression was tested many times, and the front two cyl were at 60 and 120. 😞

sorry! I meant *fuel pump, not water pump. LOL Its been a long day...

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17 hours ago, VicSev93 said:

 it would shut off randomly, and it would also not rev above 2k rpm (I honestly dont know why, any thoughts on this?)   😞


This has nothing to do with low-compression on one cylinder! That’s because one cylinder would not be fine one moment and low the next (causing sudden shutdown)! Also other 3 cylinders have more than enough power to redline bike. Look at all the cripple-600/450 racers, one cylinder has 0-compression and engine still makes 90bhp and redline just fine.

 

Suddenly dying is due to something that changes... suddenly! From one moment to next. Most likely electrical. Could be wire in harness with short. Hitting bump just right can cause bare wire to touch neighbor or frame.  Effective (fast and inexpensive) troubleshooting comes from testing by taking measurements and coming up with numbers. And comparing those numbers with specs in manual. With modern bikes, more and more of these tests (and issues) are purely electrical.

 

I can’t even think of any mechanical problems  I’ve had with any bikes in past 5-years of racing. They were all electrical, even after crashes. Crank sensor, TPS sensor knocked out of whack, clogged injectors (have to measure flow-rate to find they were clogged), cam-sensor caused ignition problems, MAP sensor had leak. Heck even wasted couple hours scratching my head when bike died and wouldn’t start. Was going to swap entire fuel & ignition system! Turned out it had run out of petrol and level-sensor in tank had malfunctioned! 

 

You’ll want to follow manual’s troubleshooting steps with measuring voltages at various places. Measuring and testing all sensors. Really helps to have oscilloscope and know how to use it. This is literally a 5-minute fix with multimeter! Most likely fuel-pump relay or fuel-pump. Did you test fuel-pump’s flow-rate at operating pressure after cleaning it? Did you measure pressure in fuel-rail? And notice if pressure changed just before bike died? Unless you bought brand-new OEM injectors from Honda dealer, they too needs to be tested and verified flow-rate is proper. New OEM injectors are no good if injector harness is shorted and not providing proper power to injectors. So, measure and test injector harness. And ALWAYS use OEM parts!!!

 

If you rebuild or swap engines without finding true cause of random shutdowns, new engine will still do same. Unless you get lucky and happen to jiggle harness just right to unground short. Or happen to replace clogged fuel-filter, fuel-lines or pump in process.

 

Find actual cause of dying problem first and fix it.  Deal with -20hp loss from low-compression later. You’ve got at least two independent unrelated problems with bike. Fixing one won’t fix other and vice-versa.

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Like DannoXYZ said, a leakdown test on the low cylinder can pinpoint the issue. That will take a lot less time than pulling the engine and swapping another one in.

 

When it dies, does it slowly idle down and die, or just shut off like you hit the kill switch?

I agree that even on 3 cylinders, it should rev past 2000 rpm. Sounds like there is another issue.

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18 hours ago, vfrcapn said:

I'd dig in to it a little more and verify compression like squirrelman says.

 

Although...it can be a little bit of a chance buying a used motor but you can get the compression checked before or after you buy. I dropped a used $300 20K mile motor from a wrecker in mine and have put 25K trouble free miles on it. I understand the rebuild it urge, but these motors are (typically) almost bullet-proof. Spend the saved money on injector cleaning, new hoses, gaskets...

 

IMG_0062.JPG

Hey vfrcapn, what fork, front wheel, triple clamp combo are you running?

Many thanks

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44 minutes ago, squirrelman said:

 if the valves are leaking you can listen at the airbox or exhaust pipe while turning the crank slowly with a wrench and hear hissing.

 

Wouldn't that occur normally anyway when cam opens and closes valves as you turn crank???

Isn't the real test to keep both intake & exhaust valves closed to see if they hold combustion-pressure?
Perhaps pressurize the combustion-chamber somehow with valves fully closed and test for leaks at TDC on compression-stroke?

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4 hours ago, paulmeisterpk said:

Like DannoXYZ said, a leakdown test on the low cylinder can pinpoint the issue. That will take a lot less time than pulling the engine and swapping another one in.

 

When it dies, does it slowly idle down and die, or just shut off like you hit the kill switch?

I agree that even on 3 cylinders, it should rev past 2000 rpm. Sounds like there is another issue.

Nah, it does both, sometimes, it dies right away, sometimes, it dies slowly, and sound worse as it goes for the shutdown. Also, the only way to even keep riding the bike without shutting it down, is constant throttle, when the throttle is let go, the engine also seems to die. Its all weird issues. I just dont know what to do. The bike did sit for over a year, there was a bird nest and spider webs, but we did clean everything out.

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Does it die when idling in garage? Or only when moving?

 

In one instance of bike sitting over several months, I found broken crank-sensor wire where rats chewed through it.

But that's obvious as oscilloscope trace showed zero signal going into ECU.

 

Your case, of inconsistent randon shutdown behavior, could be loose connector, corroded terminals, shorted wiring, causing issues with fuel & spark. Simple enough to test signal at all ECU wires and see if they are within spec. Either ECU is not receiving proper signal from sensors or it's sending out incorrect signal. Extremely easy to check.

 

Your best bet is to download manual. Then go through every EFI system test one-by-one. Something will obviously jump and SCREAM as out-of-spec. It could be as simple as this (example only, not actual wire on bike):
 

1. test voltage at XRW-GHW wire with key ON, engine not running. V=battery voltage

 

And you get only 1/2-battery voltage or zero. Obviously need to check that circuit a little closer. Without testing, you'd never know that your fuel-pump or injectors or ignition-coils are getting less power than they should. I'm still leaning towards fueling issues with pump, relay or injectors.

 

 

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the hissing test is no-cost and doesn't need gauges or an air compressor like leak-down.   it's easy to feel the piston on compression stroke approaching tdc where there shouldn't be any hissing sound.

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8 minutes ago, squirrelman said:

the hissing test is no-cost and doesn't need gauges or an air compressor like leak-down.

 

But it tests nothing because it can't distinguish between correct and incorrect behavior. Engine will ALWAYS cause hissing at intake/airbox and exhaust when you turn crank. Engine with good valve-seal OR with bad valve-sealing.

 

Now if you've got degree-wheel attached to crank, yes, you can determine that it's hissing at 10-degrees sooner than normal and yes, that would indicate bad valve-sealing. But even with degree-wheel, unless you've got those exact numbers on-hand, how would you know if hissing was early or not?

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19 minutes ago, DannoXYZ said:

Does it die when idling in garage? Or only when moving?

 

In one instance of bike sitting over several months, I found broken crank-sensor wire where rats chewed through it.

But that's obvious as oscilloscope trace showed zero signal going into ECU.

 

Your case, of inconsistent randon shutdown behavior, could be loose connector, corroded terminals, shorted wiring, causing issues with fuel & spark. Simple enough to test signal at all ECU wires and see if they are within spec. Either ECU is not receiving proper signal from sensors or it's sending out incorrect signal. Extremely easy to check.

 

Your best bet is to download manual. Then go through every EFI system test one-by-one. Something will obviously jump and SCREAM as out-of-spec. It could be as simple as this:
 

1. test voltage at XRW-GHW wire with key ON, engine not running. V=battery voltage

 

And you get only 1/2-battery voltage or zero. Obviously need to check that circuit a little closer. Without testing, you'd never know that your fuel-pump or injectors or ignition-coils are getting less power than they should.

 

 

Well, sadly,

it dies both, during riding, and during just sitting and running. 

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1 hour ago, VicSev93 said:

Well, sadly,

it dies both, during riding, and during just sitting and running. 

Surprised there has been no mention of what your Fi light is doing! Is it flashing any code?

Might pay to clear any memorised ECM fault codes, then start the engine and see if any codes appear. Be curious to know if you are getting any TPS codes Throttle Position Sensor.

Try also monitoring with a voltmeter probing the Black/White wire from the ESR (engine stop relay). This is the main 12v supply for ALL your EFI stuff. Run the bike and if the engine cuts out you want to at least be sure of what this voltage is doing.

Also check as many Grounds as possible. Make sure they are near zero ohms back to the battery Negative terminal.

Also with engine running make sure your charging voltage is ok. 13.5 to 14.5v thereabouts at the battery. A dying battery or one not being correctly charged can cause strange issues.

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1 hour ago, DannoXYZ said:

 

 

But it tests nothing because it can't distinguish between correct and incorrect behavior. Engine will ALWAYS cause hissing at intake/airbox and exhaust when you turn crank. Engine with good valve-seal OR with bad valve-sealing.

 

Now if you've got degree-wheel attached to crank, yes, you can determine that it's hissing at 10-degrees sooner than normal and yes, that would indicate bad valve-sealing. But even with degree-wheel, unless you've got those exact numbers on-hand, how would you know if hissing was early or not?

 i don't agree, and believe valve air leak has nothing to do with with valve timing as long as it's within standard specs.  you can visit my website: imightbeanidiot.com

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2 hours ago, DannoXYZ said:

 

1. test voltage at XRW-GHW wire with key ON, engine not running. V=battery voltage

??

Hey Danno can you enlighten me. What is XRW-GHW wire? Never heard of this before!

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