Topic: more 500 racer developement

[Sam Green Racing]

I had an idea that would be the reply that's where the eggs came in. 

Sam

[paulages]

yossef-

wow... really good info about the tensioner. i'll likely be going this route next time i tear down the 718cc engine. as you know, i'm not racing it, but i do tend to keep it high in the rev range so i can see that it might wear a little faster than a stock motor..  as you know, i ran into valve-to-piston clearance issues recently as well, and i can't help but wonder if my tensioner is adequate. when i mocked the engine up, i had about .090" clearance on the intake if i remember right but when i mis-timed the cam upon reassembly i had some serious contact issues. anyway, don't mean to hijack your thread-- great progress on the engine. can't wait to see the dyno report and a thread about your re-worked tranny. 

[turboguzzi]

hei paul, long time!

is your bike running again?

Droped the cyl block on the motor today and already feeling good about having taken this step with the tensioner.

So I am pushing ahead, later this evening the valves should be back on the head but before closing the motor, i need to take the head to welder to tack the ears on the new manifolds for the Keihin CR's.

Went shopping for throttle cables,  had to shorten the gudgeon pins, turned some extra air jets for the CR's, in short, having very full evenings/nights. Might have to leave for two weeks in the USA for work, so am trying to complete as much work as possible for next race.

Might end up in SF early august,

Cheers

TG

[paulages]

Staying busy, huh? No, I haven't got the bike running again yet- just got back yesterday from russia and finland. I did get my head gasket and sealing rubbers in the mail while I was gone, so it'll go back together in the next couple days.

Let me know when you're gonna be in SF- I might be there around the 13th or so.

[turboguzzi]

busy indeed

went to my good old welder, charges 15$ for everything, no matter what. finished in one go the manifolds for the CR's.

shame that the guy is going on pension soon and shut down his little backyard biz.

Run home to see how the CR's fit and it looks lovely, better than with my VM's.

in the shot through the port, I positioned the flashlight at the valve seat and it's an amazingly straight shot. the little black gap in the middle is due to the carb stubs being too big, going to fill that up with hi temp epoxy

Should close the engine in the weekend and maybe start it up.

Keep you fingers crossed.

TG

[bwaller]

Another nice job TG.  Are those 650 intake rubbers??

[turboguzzi]

No Brent, these are made by an italian company, ariete. They are 35mm ID at both ends,

from Paulages it sounded like the 650's had differnt diameter's, didnt want to risk it.

If it's of any help, with the 26 VM's I managed to use the stock 500 manifolds.

TG

[bwaller]

Thanks, yea they work with the 28's too.

[Rod]

first year I modified the stock to get 12:1 and good squish (on the right) it lasted ecceptionally well
in the middle there's the last piston by TKRJ that didnt do so well. it not only smeared itself but the gudgeon pins wore really badly. Was not impressed
on the left there is the new 57 pisotn I am fititng after an overboe. very modern design, thin rings, low friction coating

last picture shows it compared to the stock CB500.

TG I wonder whether the differential performance of the pistons is an illustration of the different properties of cast vs forged. I know that the aftermarket trick suppliers like to emphasize the strength of forged, fancy profiles and coatings etc but there is no getting away from the fact that they are less dimensionally stable with high temperature than cast - and therefore require larger clearances. I had the privilege many years ago of having work done by a great tuner (Les Ryder) who worked in race development for Jaguar in the years they were consistently winning Le Mans, he also worked with Vincent Piatti of twin-spin fame with whom he did head development on the flat-track Triumphs which had success in the 70's. He liked cast pistons "you can run them tight, and rev them high".

[turboguzzi]

Hi rod

regretfully i am not a professional tuner who has built countless engines and can tell you the pros and cons from personal experience.

Today, with nikasil coatings and no iron sleeves, maybe the whole expansion rate issue is not so critical anymore, not sure.


In any case, got around to mount the CR's, was quite a push to get it all done, but as a reward, the motor started right up after just a few seconds on the rollers starter and actually even idled better than with the VM's. before starting i synchronized the carbs roughly by turning the motor with the roller starter and it paid off.

Cant really gas it in my underground garage so it'll all continue in the dyno room.

TG

[Bill/BentON Racing]

TG,Great pics and post,I am ready to see what she will dyno,too bad about your welder,what coating is on the piston skirt? Bill, 750s all together different cam chain tensioner set up.But solutions exist for them too.

[turboguzzi]

pic an XL125's piston for dresda

i never used but my tuner friend tells me that the dome has to be truned down a bit as it's too much for the 500/4 chamber.

some winning machines were built with these, so not a bad choice.

of course youll need to machine the valve pockets too.

TG

[turboguzzi]

stock 500/5 with 15 degs band machined around to make squish with the stock head -1.6mm machined from block, 12:1 CR

run this for 1.5 seasons, went pretty well considering cost 

[turboguzzi]

tkrj CG125 piston

japanese company but had issues with pin steel quality and skirt life.

[DresdaHonda]

Thanks TG
Is the XL125s piston forged or cast ?

I been looking at the net and did not find the forged ones -where to bye them ?

and to compare the price
-where did you bye the pistons you are using ? -looks very light

-Are you using stock rods ? or Carrillo's or from another Honda ?
-I'm asking because i know the rods, I have, have been at 13000 rpm (the owner before me)

Dresda

[turboguzzi]

Thanks TG
Is the XL125s piston forged or cast ? CAST

I been looking at the net and did not find the forged ones -where to bye them ? Dont know....

and to compare the price
-where did you bye the pistons you are using ? -looks very light.  those very light pistons have a VERY low crown, you will need to take off the block some -3mm = no cam chain tension, so unless you are willing to do a lot of work like i did to the cam tensioner, i would say forget about them....

-Are you using stock rods ? or Carrillo's or from another Honda ? Stock rods, four seasons, lots of 13K rpm,  no problems.
-I'm asking because i know the rods, I have, have been at 13000 rpm (the owner before me)

Dresda

[DresdaHonda]

Well I`m ready to make the work, For me it's just a matter of lightness in pistons.
-and ofcouse strength.

Dresda

[DresdaHonda]

So far I find this types of pistons

XL250s piston:
www.cmsnl.com/products/13101-471-405-piston_13101428013/

CB500 pistons:
www.d-mengineering.co.uk/store52/agora.cgi?cart_id=3461625.9339&product=CB500/4&xm=on
www.cmsnl.com/products/pistonkit-025-oversize_00000kit0106/

Any one have any experience with cmsnl and d-mengineering ?

Dresda

[Retro Rocket]

i have bought from CMSNL and they were great..

Mick

[DresdaHonda]

Hello Retro Rocket
Have you been racing with cmsnl pistons ?

To TG
Are your pistons this 199,99 USD. pistons from Takegawa ??

www.minimobracing.com/store/Bore-Kits-and-Performance/c55/p1538/Takegawa-57mm-Scut-+R-Piston-Kit---CRF50/product_info.html

Dresda

[turboguzzi]

crf pistons are 13 or 14mm pin i think, you need 15mm

takegawa is a minibike boutique and their prices are indeed crazy

i ordered cheap 57mm from an asian suplier but had a pretty bad experience with the seller, so cant recommend him, neither want to give him free publicity, but they are not hard to find. I think that howell had a good cheap source.

I will repeat this again, some winning bikes here are built with cast, stock xl125s pistons, you can shorten them for lighter weight, fit tapered pins, etc.

TG

[Howell]

Hello Retro Rocket
Have you been racing with cmsnl pistons ?

To TG
Are your pistons this 199,99 USD. pistons from Takegawa ??

www.minimobracing.com/store/Bore-Kits-and-Performance/c55/p1538/Takegawa-57mm-Scut-+R-Piston-Kit---CRF50/product_info.html

Dresda

Takegawa pins are 13mm , and they are indeed very expensive , our pistons with 13mm pins costs € 25,=  
CMSNL is a dutch company , reliable but expensive.
Search on Google with: pistons 57mm , 15 mm pin
http://www.ooracing.com/store/index.php?act=viewProd&productId=772
http://www.thefind.com/garden/info-57-mm-piston-kit
http://www.scooterdomain.com/category_s/746.htm

[turboguzzi]

Rene

dont forget to tell dresda that you got gsxr rods with bushed ends in your 500 

Cheers

TG

[Retro Rocket]

Hello Retro Rocket
Have you been racing with cmsnl pistons ?

To TG
Are your pistons this 199,99 USD. pistons from Takegawa ??

www.minimobracing.com/store/Bore-Kits-and-Performance/c55/p1538/Takegawa-57mm-Scut-+R-Piston-Kit---CRF50/product_info.html

Dresda

No, i do not race , i bought rear guard side covers and other bits..

Mick

[DresdaHonda]

Ok, so the gsxr rods is 111,5mm (center to center)
What lenght is cb500 and cb550 rods ?

Dresda