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'95 engine rebuild kit?


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I picked up a basically free engine out of a 95 vfr750.  I'm in the process of going through it to see whats what, and to also hopefully improve on the performance.  If I can find a quality machinist who is willing to do the work I'd love to go to the 837cc.  That said, I'm trying to gather up as much information and resources as possible.  I've been doing a good bit of searching and reading over the last few months and really haven't found any concrete info, just a lot of hypothetical and desires.  Even searching for a gasket kit I haven't found a good source.  Anybody have any directions to head?  Machinist to recommend (that is still in business)? Parts supplier?

 

I appreciate it!  I promise I'm not being lazy, just fed up with not getting anywhere.

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The one member I know of who had an overbore is @douglasthecook but donot recall what the outcome was.

 

We had a guy here a long time who advocated UNLEASHING THE FACTORY POWER :laugh: with a change in pipes, but never did backup his claim.

I beleive that there is not much to gain out there; rejetting the carbs did gove a bit more midrange oommph but if it is raw power you want, get a Fireblade or Beemmer S1000RR...

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Thanks, I'll touch base with him and see what he found.  

 

I'm actually pretty happy with the power of my vfr, and I'm absolutely in love with the music flowing from a V4 exhaust.  I'm wanting to enhance this engine just because I can, just because it would be fun.  I'm planning to throw a set of tyga pipes on and tweak the carbs, but I honestly am ok with never having the power and speed of a liter bike.  That said, I would totally buy an RSV4 if I had the cash!

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I, too, would like to find a 4th Gen gasket set as I have a long-term plan to do some engine work.

If you are getting new pistons (837cc route), why not bump up the compression ration?

Increasing the compression ratio increases the mechanical efficiency (limited only by fuel detonation), thus increased HP.

Brian

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Brian, that's the plan.  I believe that needs to be 12.5:1, but I haven't found concrete numbers.  I also assume that higher compression ratio would require higher octane fuel than any pump gas, which could detour me from that route.  ...Although I do love the smell of race fuel...

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Athena Gaskets show a part number for the VFR750F. They are an Italian company and do all their own manufacturing. I spoke with them at the Milan Motorcycle Show back in 2016 and they were very helpful in finding a few things for my VF1000R. Here's a link.

 

http://www.athenaparts.com/eng/products/view/6474/complete-gaskets-kit

 

They have a US office in Bohemia NY. If you click on the link they show a contact button at the top, in there is a contact number and a Technical Help number. Would be worth a call to see if they can supply one, although I think you would have to order from some one like Bike Bandit as I don't think they will sell direct.

 

Hope this is of some help.

 

 

 

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5 hours ago, davfr said:

...require higher octane fuel than any pump gas, ...

Actually, that's not quite correct.   My plans are to build an engine to use E-85 (which may not technically be "gas", but the octane rating is .... "race gas" level).   The hotrod car guys love it, don't see why WE can't burn it (with modifications) in the bikes.  I've read that the car engines burning E-85 are more like 14:1 or huge inches of boost.  Higher power level, a bit less mileage (YMMV 😀).

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I can personally confirm that a stock 4th gen runs totally and utter CRAP on E-85...  :goofy:

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Hi Smack. I'm sure you've done the research on E-85 but if you haven't strongly suggest you do. Apart from its cleaner burn, octane rating of 105, and racing application. Frankly, for normal use IMO its shit.!

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Not to mention the smell of ethanol... I can't stand the smell of it - especially when you compare it to the sweet aroma of race fuel.  I've got buddies that run race fuel in their lawn mower just for the smell of it.

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7 hours ago, Grum said:

Hi Smack. I'm sure you've done the research on E-85 but if you haven't strongly suggest you do. Apart from its cleaner burn, octane rating of 105, and racing application. Frankly, for normal use IMO its shit.!

For road use it would require much more frequent fill ups.  Despite the benefits, it's not for me.   

 

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TTS does still sell the kit - "Yes, the pistons are made to order. Price is £600+vat the set with rings pins and clips. You open out the stock head gasket."

 

Kinda hate to pay the vat if I can just order direct from JE.

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Well on this they're right--and might be interested to learn what TTS was doing with the VAT money it collects "on behalf of the government" if it wasn't actually given to the government...

 

My FP (the red VFR I rode to Assen all those years ago!) has the TTS 837cc pistons in it.  Frankly, I notice no difference, probably because I have never thrashed the bike on a track, where seconds count.  I'm sure there is some benefit, but it's only a 12% increase in displacement, so there's not a huge amount of potential there anyway.  Not on the scale of forced induction, anyway.

 

Years ago, when Brian Law's Dynamo Humm was helping to hot-rod VFRs all over North America, I asked him why the hell he had to buy the JE piston kits from TTS in England when they were manufactured in California, and he explained that TTS had provided the specs to JE, so JE's position was that the pistons were TTS' to sell.  Brian sure re-sold enough of them, so if it were in any way possible for him to buy them directly from JE Piston, I'm sure he would have.  I think Brian did get his 870cc kit (for the RC46, included new sleeves) manufactured directly, but that was his own design.  (I'd love to get an uninstalled set of those babies!)

 

Ciao,

 

JZH

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There’s a good article in the latest edition of Practical Sportbikes that covers a guy tuning an early VFR750F engine including a 2mm overbore and head work - dyno had it at 107 bhp at the rear wheel 

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On 11/12/2020 at 12:20 PM, Thumbs said:

There’s a good article in the latest edition of Practical Sportbikes that covers a guy tuning an early VFR750F engine including a 2mm overbore and head work - dyno had it at 107 bhp at the rear wheel 

is that in the December 2020 edition?

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2 hours ago, davfr said:

is that in the December 2020 edition?


yes .... the one with the Bimota Tesi on the front 

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