Yoshimura Reissue for the VF500F

I agree, in terms of engine performance a 4-1 seems like the way to go over a 4-2 system.

 

Are there any differences with the 86 Valves/springs?

They shows different part numbers than the 84/85's

 

Yes, I believe the '84/'85 is different than the '86 (as you note the part numbers are different) - for reference, the VTR250 shares the same valve spring part numbers as the '84/'85.

I'd be interested to hear other owners' opinions on whether it is better to go with the '86 head grafted onto the earlier engine design or to revamp the earlier heads (both strategies using hardfaced cams, rockers and new valve spring kits). If the '86 is the way to go then these are the heads that I will source and send to the valve spring company.

Not to muddle things up but I have read that the '86 was a 'de-tuned' version (in terms of HP output) of the earlier model's engine design - of course this could be based on the lower rev limiter...any insight would be much appreciated...thx!

 

My understanding is that the '86 had hotter cams to make up for the smaller carbs. I don't know anything about them being de-tuned versions of the the '84/'85 beyond that.

-Jake

 

My 86 has Hot Cans

 

I could donate a cylinder head for them to use, maybe even the set.

 

Much appreciated! What year are the spare heads, that you have, and what condition are they in?

 

They're 85 heads, the valves aren't in the greatest shape, in fact, I'm probably taking the best 8 out of both sets to run on my bike for a while. The tips are messed up from either over-revving, lack of maintenance, or both. I can re-assemble at least 1 head full of valves. The springs all seem to be intact.

The rockers and cams are TRASHED on the spares, verifying the top-end oiling problem exists on the 500's.

 

Thank you for the post.

I really appreciate your offer but I think I'll see if I can find a set of used heads ('84/'85 or '86 TBD - based on which is the best to go with) that are in okay shape to send to the valve spring company.

On the topic of top end oiling issues - from what I've read and what Honda Tech's who worked on these bikes back in the day have told me - the best way to insure longevity is to - let the bike properly warm up before riding, use a high grade of motor oil (i.e. Honda GN4) and perform the valve maintenance per the Factory schedule. I think more often than not the VF500F suffered their noted lack of longevity from their owners not following these three simple guidelines.

 

Besides the proper maintenance thing which is obvious the rest is all news to me.

Never heard of those being the issues.

 

Yes, it is very important to let these engines fully warm up...don't ride with a cold engine.

Top picks for motor oil: Honda GN4 and Valvoline Max-Life* in 10w-40.


*the Valvoline Max-Life is a Dave Dodge recommendation

 

Are those synthetic oils?

A mechanic put Sythetic oil in my bike after I asked him not too and my Oil pan started to leak shortly thereafter.

I wouldn't recommend synthetic oil for a bike that is old/high mileage or hasn't seen synthetic for most of it's life.

 

Honda GN4 is conventional. Valvoline Max-Life is a mineral/synthetic blend.

I use Honda GN4 in my '84 VF500F. I posted the Valvoline Max-Life as this is Dave Dodge's pick. I asked him awhile back for any tips or tricks regarding maintenance and he recommended the Max-Life for its 'cling' properties - 'leaves a good film of oil on the parts when the engine is not running'. He also recommended to set the idle speed between 1000 and 1100 rpm.

 

Woah! Really?

Setting it lower???

Won't that lower oil pressure at idle?

 

It is for that reason that I don't run a full synthetic in any of my '86 Interceptors. I am running and have been running a semi-synthetic for years now with no leaks or problems. I figure that way, I get the best of both worlds.

 

As am I.

Motul 5100 semi-synth 10w40 and 15w50 in the dead of summer when it's crazy hot out.

 

Back on topic.........

I doubt that Yosh USA would have anything. That data would be stored in Japan. The 4-1 Yosh systems were never available in the US, so you might try contacting someone in Japan to see what they can do for you. You've had good luck with making contacts so far!

 

Thank you Jamie. I will give it a try.

On the intel front - any chance you have a photo, in the archives, of this enigmatic exhaust?

 

I used to. I think I lost it about 5 computers ago, but I'll check again and see what I can find.

 

Great, thanks for checking.