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Anything wrong with my engine?


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First off. Hello! my name is Eward, and im new to the forum!

 

So i bought a 91 VFR750 for 600 bucks and it wasnt running right, i figured out it was just a spark plug so installed 4 new ones 

and before that i already cleaned the carbs because it was sitting for some time already. As of right now its pretty drivable but on the highway its kind of jerky.

I made a video to make it easy to diagnose or at least hear what the motor sounds like right now, it has some kind of ticking but maybe that's just VFR

It has 50.000 KM's or 150.000 km's😂don't know. Here's the link!

 

VFR sound on youtube

 

Thanks in advance!

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17 minutes ago, Dutchy said:

Dat klinkt niet best....

Heb je enig vermoeden? Sinds de nieuwe bougies erin zitten komt die goed op toeren en stottert die ook niet echt meer 

 

Het geluid wordt ook wat versterk door de opname met de telefoon, de tik is niet heel heftig. Maar als ik het gas steady op 3000 toeren(bijv) houdt dan loopt die wel wat raar. Hij verbruikt ook flink..

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Sounds like it's running on three cylinders.  Do you get sparks from all four plugs?  Do all four exhaust tubes get hot at the same time?  If not, it's either the carbs still clogged or (worse) a valve issue...

 

Ciao,

 

JZH

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On 11/3/2018 at 6:44 PM, Auspanglish said:

 

 

 

:beer: We're Dutch, not Swedish....   

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4 hours ago, JZH said:

Sounds like it's running on three cylinders.  Do you get sparks from all four plugs?  Do all four exhaust tubes get hot at the same time?  If not, it's either the carbs still clogged or (worse) a valve issue...

 

Ciao,

 

JZH

 

 

what the man said....

Either touch them by hand or point a laser heatreader on them...

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I am not a mechanic, but it doesn't sound too bad to me. If it was running on 3 the idle would be rougher.

 

If it runs OK on the highway, but is jerky, it might be the final drive or possibly sticking throttle cables, not the motor itself.

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Sounds a bit lumpy but the revs seem to rise fine and the bike doesn't appear to be vibrating overmuch...

 

Check all four exhaust pipes are hot by spraying water on them once the bike is warmed up.

Have you synchronized the carbs properly?

Is there a hole in the exhaust somewhere?

Any popping noises when backing off the throttle or engine braking?

Are you experienced with carburetors?

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All 4 cylinders seem to be firing but sounds lumpy or uneven. I would guess it needs carby balance but drop into your local bike shop and they might listen to it and advise.

Jerky running might be a stretched chain. Chains do not stretch uniformly. In my experience a chain lasts around 20-25000km and before that stage it is difficult to adjust correctly because different parts of the chain are stretched more than others. Eventually you feel the bike jerking when you are just cruising slowly with steady throttle. Worn chain also makes it difficult to perform smooth gear changes. You may also need to replace both front and rear sprockets - normal maintenance.

Nice bike. Good luck.

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Thanks so much for all the responses. I tried syncing the carbs with one of those DIY carb sync tools with a 4 tubes and and some ATF but the carbs are so out off sync that on tried to suck in the fluid, which i prevented gladly. So i'll try it sometime this week with another tool. And the rattling is pretty profound, but it seems its not coming from inside the engine. Sounds like a good plan to check header heat indeed.

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  • 2 weeks later...

Alright guys, i figured out why it was rattling like in the video. So i checked out the front headers and there we go, the left front header bolts where never there.... Well one barely in. So i put a new one in and fastened them nice and thight. No more rattling! I think that was part of the problem why it was running bad because it was backfiring right there, that one header was just loose

Winter has arrived here and its getting bloody cold so i put her inside for now. When i got time i'll check the carbs sync again and i have to get started on that head bearing job.

Sent from my ONEPLUS A3003 using Tapatalk

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So you bought a good bike cheap!  Very Dutch!!!  :beer:  

 

 

 

Yes it is bloody cold, that's why they invented Oxford heated grips and thermal underwear and fleece! :tongue:

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Cannibalize an aftermarket car seat heater and MacGyver it into your jacket and connect it to your battery.

Works like a charm

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  • 4 weeks later...
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My ‘95,16.6km/L(6L/100km), check air filter, not likely idle mix screws would have a big effect unless they were so “rich” that an idle would hardly be possible..

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PS.    Little Sub-air filter on there can sometimes have quite an influence, although they usually fall apart & don’t filter at all, so unless some previous owner replaced that element with one too restrictive ..you get the idea I’m sure

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The Honda thermostat is a tricky little item.  At some point in time the OEM thermostat will fail, however you never know what the failure mode will be, some of them fail in the full-closed position and some of them fail in the full-open position while others fail in a way that reduces their range of motion to less than the normal range.  The truth is that when you start to see odd temperature behavior from your VFR it's time to replace it.  Good luck with the bike.

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Not sure if your 3rd gen (1990-1993) share the thermostat and sender with the 4th gen (1994-1997).

But the meter on my 4th gen would RARELY go over the mark you drew in red.  And that is in 19 years/100.000km......

 

I never monitor(ed) fuel usage, and a lot depends on how you ride/rev.... So yeah, do check if the pilot screws are on a "normal" setting 1st. But then again, you donot know if some prior owner had the needles changed.

If you have a dynometer shop nearby, ask what a simple test run (also checking a/f ratio) would cost you. 

 

 

PS Once I give my SP2 the spurs,  1:8 is not unheard of... :goofy:

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Im trying to find a new Thermos on the internet but it's rather hard... Is it a hard thing to find in europe?

 

Or could i fix it myself in any way? i'll try to take it it out and see what's up.

 

Stupid thing is im able to find a few second hand thermostat's with housing and all but those might as well be stuck open!

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