660 and other motor questions.

Ickis · Post by **Ickis** » Thu Mar 31, 2011 3:12 am

So I'm piecing together a 660 (got most of the big stuff already). FZR600 bottom end, YZF600r top using the YZF600r rods. I have a few questions not about the swap, but about some things I want to do. So I plan on advancing the timing by 5 degrees, pretty standard thing that helps out with the over all power. I also plan on doing the Ford Escort ignition coil mod. Now, I understand, due to advancing the timing, running a higher octane, especially during summer time is advisable. Now, the thing I'm REALLY curious about is upping the compression. Since I'm using the YZF600r rods, I've got to use a 3mm spacer plate (the same one DRU86) which brings the compression to 12.76:1. I'm wanting to run 13.1:1, I'm curious what peoples thoughts are on this... With the added compression, I would once again need to bump up the octane (92 is the highest here). Now, assuming clearance is good, I'm worried about the stress the extra compression would add to the con-rods taking into consideration the engine is also now stroked which adds it's own stresses to the con-rods. So basically I'm kind of lookings for a pros and cons to doing 13.1:1 comp.

On another note, I've read that putting an intake cam on the exhaust is a cheap way of adding a little extra performance. However, I haven't found anyone that's actually done it. Anyone have additional info on this?

yamaha_george · Post by **yamaha_george** » Thu Mar 31, 2011 3:28 am

I,
the con rods were built for that stroke by definition surely, and going up 0.34 compression which is what? less than 3% I would say is a safe move.

As to the cam swap one of the FZR racers boys may know that , like you I have read that but do not know any one who has actually done it.

Timing advance I would read REELRAZORS method on that rather than the silly expensive mag key

Ickis · Post by **Ickis** » Thu Mar 31, 2011 3:34 am

YG, just the person I wanted to hear from! I'd actually being going up from 12.1:1 (yzf600r stock comp) so it'd be going up 1.0.

reelrazor · Post by **reelrazor** » Thu Mar 31, 2011 3:37 am

Me, I plan on having the FZR rods bushed down to the YZF wrist pin. Already checked with my local (good) automotive machine shop. Very standard practice, and furthermore-cheap at $20 per rod. Eliminates that spacer plate-which has always seemed a hack to me.

Recip weight gained in bush countered by decreased weight of wrist pin. and will drop with clearance machining the pistons for valve clearance-

I've got megacycle 276x3 cams. Static comp. will go up, but dynamic comp willl probably allow pump fuel.

Freestyle72 · Post by **Freestyle72** » Thu Mar 31, 2011 4:56 am

Ickis wrote:So I'm piecing together a 660 (got most of the big stuff already). FZR600 bottom end, YZF600r top using the YZF600r rods. I have a few questions not about the swap, but about some things I want to do. So I plan on advancing the timing by 5 degrees, pretty standard thing that helps out with the over all power. I also plan on doing the Ford Escort ignition coil mod. Now, I understand, due to advancing the timing, running a higher octane, especially during summer time is advisable. Now, the thing I'm REALLY curious about is upping the compression. Since I'm using the YZF600r rods, I've got to use a 3mm spacer plate (the same one DRU86) which brings the compression to 12.76:1. I'm wanting to run 13.1:1, I'm curious what peoples thoughts are on this... With the added compression, I would once again need to bump up the octane (92 is the highest here). Now, assuming clearance is good, I'm worried about the stress the extra compression would add to the con-rods taking into consideration the engine is also now stroked which adds it's own stresses to the con-rods. So basically I'm kind of lookings for a pros and cons to doing 13.1:1 comp.

On another note, I've read that putting an intake cam on the exhaust is a cheap way of adding a little extra performance. However, I haven't found anyone that's actually done it. Anyone have additional info on this?

Rods will be fine. But remember you can't use your redline of 14,000 RPM anymore. You have to drop it to 11,500 or 12,000 due to have the FZRs stroke so you have to respect the FZRs redline.

I also have a 660 with a +1mm overbore. Carillo rods, wiseco pistons, lightened flywheel, valve job, balanced crank etc. And I can still only run it at 12,000 RPM. I want to bump it up to 14,000 because I love my REVs but even with all that work it was recommended I respect the FZRs redline because ultimately the longer stroke will up your piston speed. So at 14,000 RPM your piston is going to be going much faster than it would normally going with the YZF crank.

yamaha_george · Post by **yamaha_george** » Thu Mar 31, 2011 2:11 pm

+5 on the lower redline FOR SURE !

the quicker the RPM the faster the stop at the end of each up & down stroke the larger the forces generated ALL of which adds to the wear on the two pins & bushes/bearings.

Add to the pistons speed shoving the piston rings around in the bore, the greater the forces applied bearing on your oil & every oil has a limit at which it works or gets torn apart.

Ickis · Post by **Ickis** » Fri Apr 01, 2011 3:46 am

So general consensus, 13.1:1 comp on stock yzf600 rods are fine as long as revs are kept at FZR600 stock redline?

yamaha_george · Post by **yamaha_george** » Fri Apr 01, 2011 4:57 am

Ickis wrote:So general consensus, 13.1:1 comp on stock yzf600 rods are fine as long as revs are kept at FZR600 stock redline?

I'
that is a pretty fair summation of what you are going to do BUT as the owner/rider/wrench you will need to shorten the periods of time between inspections for wear!

What you are building I personally would describe as a "race" spec engine & that DEMANDS extra vigilance on your part if this is going to be a great experience and not a PITA.

Old "Blue Streak" I used for friday/saturday night street dragging/bragging and that engine (2 stroke mind you ) came down every 6 weeks no if but or may be BUT 26 years later she is still no slouch and all she has had done in the way of "major" work was two sets of rings.

In the case of your engine apart from the initial err shall we say trial period of a two weeks with daily rides to listen & feel her out may need an inspection mid riding season just to add to you warm fluffy comfortable feel and then if everything is still all good a check @ the end of the season then annually BUT always riding aware!!!!

EDIT:-
One thing no one has mentioned is the fact that the rods need to be balanced(ie all weigh the same) as do the piston & ring assemblies (with wrist pins ).

We used to shot blast rods to harden the surface and smoothen them for gas dynamics. What is the current thoughts on this practice?

EDIT 2
http://www.fzronline.com/design/bweight ... zr400.html

is worth a look as further down the page is stuff about 600 & engine mods done by racers

and this link when you come to your jetting :-

http://www.saltmine.org.uk/martin/jet_sizing.html

Ickis · Post by **Ickis** » Fri Apr 01, 2011 11:53 pm

YG, thanks for the advice on taking the bike down every 6 weeks, I probably wouldn't of thought to do that. Also, I planned already on balancing the crank, pistons, rods and so on. I just can't wait until next Sunday. I got an proverbial ace up my sleeve thats in the mail, and like a few other things I've got planned/working on I haven't yet seen it done by anyone on any of the FZR forums. I'll take pictures and post a how-to, because I think some people might be very very interested.

yamaha_george · Post by **yamaha_george** » Sat Apr 02, 2011 3:49 am

Ickis wrote:YG, thanks for the advice on taking the bike down every 6 weeks,

I,
I think you read that wrong or maybe I did not make it clear enough that 6 week teardown was on a 2 stroke motor,!!! I apply the rest of what I said to 4 strokes.

dru86 · Post by **dru86** » Sun Apr 03, 2011 8:03 am

Your redline is limited basically by you piston speed, which is your stoke x rpm. The higher the speed of the pistons the more strain and the faster your motor is going to wear. Since the 660 uses the fzr600 stroke it has to use the fzr600 redline to keep to the same piston speed.

What kills rods is not compression but tension. This is greatest on the exhaust stroke(since there is nothing to compress against) as the piston comes up to TDC. Again the faster the motor the higher the tension. Lighter pistons will help here.

Realrazor: You can't bush down to the yzf600 pins as they are 1mm bigger than the fzr600 pins. If your bored the fzr rods without using bushes you would have to remove 1mm. If you bushed you would have to remove 1mm plus the thickness of the bush from the small end. I would advise against bushing fzr600 rods as the fzr600 small ends are pretty weak already, yzf600 rods are stronger anyway.

Ickis · Post by **Ickis** » Mon Apr 04, 2011 12:00 am

Dru, why'd you go with 12.7:1 comp vs 13.1:1?

dru86 · Post by **dru86** » Mon Apr 04, 2011 9:01 pm

From memory it was because i had 3mm plate sitting there. 13.1:1 should be fine as the wiseco 630cc runs 13:1.

As for the cam swap you can do this it will gain you slightly more lift on the exhaust side. How much power difference this will make i don't know. What I've now got done is I got a pair of intake cams sent of to a cam grinder here. They ground down the base circle allowing the cam to have more lift and slightly more duration. Cost $120 each cam to get each reground.

Ickis · Post by **Ickis** » Tue May 17, 2011 11:12 pm

I figured I'd make a visit back here and ask another Cam question. On a similar note of using two intake cams, I've read varying opinions (but with no facts) as to whether FZR400, FZR600 and YZF600r cam profiles are different. I've seen multiple times that FZR600 cam are more aggressive than YZF600 or FZR400 cams. Although everyone seems to agree they are interchangeable. Now seeing as how I got two FZR600 motors torn apart at the moment and prepping to part out. I figure before I get rid of the cams, I'll see if anyone has some actual facts backing that the FZR600 cams are more aggressive.

yamaha_george · Post by **yamaha_george** » Wed May 18, 2011 7:36 am

Ickis wrote:I figured I'd make a visit back here and ask another Cam question. On a similar note of using two intake cams, I've read varying opinions (but with no facts) as to whether FZR400, FZR600 and YZF600r cam profiles are different. I've seen multiple times that FZR600 cam are more aggressive than YZF600 or FZR400 cams. Although everyone seems to agree they are interchangeable. Now seeing as how I got two FZR600 motors torn apart at the moment and prepping to part out. I figure before I get rid of the cams, I'll see if anyone has some actual facts backing that the FZR600 cams are more aggressive.

I,
I cannot comment here on personal experience as i have not put 600 cams in a cam specialists hand and asked for a breakdown of data.

What I can tell you is that the racers of 400's that I respect for sound common sense & judgment on "racer law" use 600 cams and if I was doing a race 400 engine i would quite happily follow their thinking without knowing the exact details.

Other than that ...............................

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