Topic: Track day bike suspension?

[DavePhipps]

okay , back again with another brake question. What is the Grimeca copy of the F05?

TG I'm not really touching the engine on this bike. I'm working on suspension and braking. Handling first then speed later.
I'm still trying to find all your HiPo threads on your bike build. You're all over the place with those.

[turboguzzi]

check also howell's racer build thread

[DavePhipps]

Will do, thanks for reminding me of that one.
Starting the rebuild today. Time for my son to get his hands dirty.

[DavePhipps]

Hey, I've got more questions!!! these aren't just suspension and brake questions though. There may a new job looming over the horizon that will allow me to do more with the bike. The son will still be riding the 500, but there is a 550 in the shed calling to me.
Now onto the fun.
Bike geometry changes. 18 inch front rim, longer and shorter forks, longer rear shocks, and alternate triple trees with different offsets. What's good or bad? Rake and trail info would be handy.
Frame On the 500/550 frames what to brace, what to get rid of and any frame related advice.
Controls Stock throttle would probably be terrible. Quarter turn throttle? Suggestions on brands?
EngineI've got a 550 engine with a 650 head sitting next to it. Dynoman make a 572 piston kit for this. Should porting be in the future for this setup? Cam suggestions, and how would all this effect my exhaust choices? For the increased air flow and larger bore would a larger diameter exhaust be needed?.
Carbs Considering future engine mods what carb size would be good? I've seem the VM26 and 29 on some and people raving and ranting about their CRs. Size and type suggestions, and where do you find the VM 26 carbs?

If there's anything else you can think of throw it in. I'm looking at WERA classes and the 550/650 engine is allowed in a few of them. Also they have more races near me than anyone else that I can find.

[calj737]

Bike geometry changes. 18 inch front rim, longer and shorter forks, longer rear shocks, and
alternate triple trees with different offsets. What's good or bad? Rake and trail info would be handy.

There are many threads on here about rake/trail, some of which include calculators to aide you in entering all the setup effects.

Frame On the 500/550 frames what to brace, what to get rid of and any frame related advice.

Depends upon your intended use. Bwaller has a very good thread about the modifications he has made on his track bike and I believe identifies where he braced.

Controls Stock throttle would probably be terrible. Quarter turn throttle? Suggestions on brands?

Try a Domino quick ratio. Utilizes a push-pull throttle assembly and allows you to tailor via included cams, the travel of the grip to your preference.

EngineI've got a 550 engine with a 650 head sitting next to it. Dynoman make a 572 piston kit for this. Should porting be in the future for this setup? Cam suggestions, and how would all this effect my exhaust choices? For the increased air flow and larger bore would a larger diameter exhaust be needed?.

Engines are air pumps. You want performance, you need air. Better flowing heads are paramount to performance improvements. Heads can also be tailored to displacement and cam changes for optimum performance gains. Web, Mega and others offer frequently used cams for street or track oriented performance. The best results will come from a balanced approach to coordinate all systems; air, fuel, combustion, valve train and exhaust together so each system is properly tuned and sized.

Carbs Considering future engine mods what carb size would be good? I've seem the VM26 and 29 on some and people raving and ranting about their CRs. Size and type suggestions, and where do you find the VM 26 carbs?

I recently got a set of CR-26 carbs from member Godferrey for a bolt-on approach to my 500/550.

[turboguzzi]

big list...

indeed, most of the info you are looking for is in bwaller's, howell's and my threads essentially.

eye to eye of about 14" in the back will set you about right, you will want triples with about 10mm less trail than stock due to the steeper head angle. good or bad? no magic figures, you will have to hit the track and see/fine tune what works for you. online calculators will not tell you how grip at tire edge will feel
bracing is tempting and i did mine, but after seeing how fast unbraced ones can be ridden and win races in the right hands, i'd say not a must. makes you feel better mostly

dont think that any of the kit pitons available out there will get you proper racing CR ratios (like 12:1 and above) as they are street oriented. Again, those threads have plenty info on the little that's out there. or start looking into all the monkey bike big bore kits with 15mm pins out there / make your own like brent.

VM26s (they are 27mm actually) can give excellent power, but if you have the dosh, then go for CR 29s, there's only one type... CR26 would be better for street use,

[DavePhipps]

Let's hope I get the new job, so I can afford all this.
Thanks for the geometry suggestion TG, and the geometry calculator info Cal.
I've been looking through all the threads I can find but I'm still at a loss for piston size and shape. I'm using the 550 cylinders with the 650 head. Dynoman has a 60mm piston kit that will give 11.5:1 cr. That may be the easiest option. I've been searching for 4 hours and haven't come across a thread where the 550 is taken out to ~600cc using the 650 head and 550 cylinders.
Cal I'll be doing lots of reading about balancing this system before I start. Part of the reason for this thread is to give me a head start on that.


 

[turboguzzi]

the reason you are not finding a 650 headed 600 racer is that its not the best option... the combustion chambers are bigger and you'll be hard pressed to find pistons with high enough crowns that will give you 12:1 compression. the dynoman slugs will give 11.5 on a 550 head not on a 650 head
not sure it would be ahrma legal either, check...
a 650 head will work with much higher displacements like paul ages 730 or something, look for his build

considering bwaller is getting 70  rwhp something out of his 550 headed 600, it's not exactly a problem to stick with a massaged stock head.

maybe the dynoman is after all your best option, deck the block and/or the head a bit and you might get 12:1 or more. never seen those pistons up close though

[DavePhipps]

Not going AHRMA, they have odd rules about disc brakes. I would have to go drum even though the bike was produced with disc, odd.

I'll go through Brent's thread again. I think I missed the piston info. My eyes are starting to glaze over from reading so many threads today.

From the dynoman website
Bore in piston kit for CB550 engines using CB650 cylinder head.

Features:
- Lateral Gas Porting
- Accumulator Grooves
- Contact Reduction Grooves
- Broached pin supports
   for superior oiling
- Made in the USA
- No re-sleeving required!
- Lightweight 168g

Not sure what they are like or how domed they are. They don't even have a picture of them. I really don't want to go super domed as it seem that it would interfere with air/gas flow in the chamber.

[calj737]

If you want great performance, you can go with 61mm pistons but you'll want to send your head to Mike Rieck. Brent used him to get that part of his motor to 70bhp. I just upped my 500 block to 59mm forged Wisecos with a Stage 3 MRieck head job. Mind you, it's not oriented for the track at all, but the street. I'm using the Cr-26 carb kit from Godferrey and a Mega 125-20 cam. I'd suspect 60+ bhp. If the hands of a competent rider, it should do right by you.

Motor is at the shop as we speak getting bored. Mike put in o/s kibble whites and did a Serdi cut on the heads. Might be a picture of the head in my 500 thread in the signature.

My goal was strong, reliable, and modern performance from a vintage frame/bike. Motor was badly seized upon receipt, so some matching was required anyway. The "extra mile" was a toss up in function over functional.

[bwaller]

D-man does have those 60mm pistons for a 650 head. They need a large dome to fill the large combustion chamber, no other choice. I don't know anyone who uses those pistons but a friend I race with bought the 60mm 1:11.5CR 550 pistons and his engine makes the same power as mine. Among other people I spoke to Buzz years ago, before he started with any 550 stuff, so I designed my own pistons and had them made.

Dr. Tom Marquardt ran his 550/650 out to the AHRMA class limit of 685cc. It was a potent combination of bike & rider. He doesn't race it anymore though. He told me he always had leaky base gasket problems at that bore size.

I think with some work my 572 could make 75rwhp, but those extra three ponies come at a high price. At this point the engine is dead reliable, and actually quite docile. I'll not mess with it .....for now! I thought about building a 550 based engine to use with a 650 head. That piece is vastly improved over the 550 head and with even larger carbs should easily push HP into the low eighties. The problem is dealing with various engine components originally built with 36-38HP in mind. I expect reliability issues would surface.  . You'll possibly have to make a pipe for that head, I don't know of any available?? The Kerker primary tube diameter is larger so maybe it could work, I never tried it against a 650 head.

My wife's 592 (61mm pistons) is a mild 51rwhp (stock carbs etc) but ended up being exactly what she needed, a wide power band, easy to ride, just like the original only with 27% more power. It's no pouch! Keep in mind the more power you make, the narrower the accessible power band becomes especially when you get into large carbs. Not that it becomes really difficult, but needs to be ridden differently on the race track.

[Retro Rocket]

big list...

indeed, most of the info you are looking for is in bwaller's, howell's and my threads essentially.

eye to eye of about 14" in the back will set you about right, you will want triples with about 10mm less trail than stock due to the steeper head angle. good or bad? no magic figures, you will have to hit the track and see/fine tune what works for you. online calculators will not tell you how grip at tire edge will feel

Actually, it is well known what trail does and having an idea of where it is is a good thing, too little trail is bad for stability and too much is bad for turn in, somewhere around 3.75 to 4 inches is a reasonably good start, You don't want triples with less Trail because you already have less trail with the steeper steering head angle, you want less OFFSET in the triple clamps to add a bit of trail to maintain stability... 

[turboguzzi]

ok, must have missed that, obviously wasnt aware that DM's pistons were designed with for 650 heads.

when the highest intake velocities are developed, piston is mid stroke far from the head, so crown shouldn't impact flow. you should see the crowns on a manx norton or G50, those were tall....

but with tall & steep crowns, it's not easy to get well controlled squish areas, so pay attention to that, makes a world of difference on how detonation prone the  motor will be.

it does sound like a relatively hassle free path then.

[DavePhipps]

Retro I'll be getting the 3d program out this weekend and make a simulation for measurements with different wheel sizes and shock lengths. OK, I'll be doing that after I work on my kids electrics on his 500.

TG after reading your post i went around and read a boatload of articles on squish.  I've seen suggestions of .06 .05 and .03.
What are the clearance you and Brent use?

Brent I already have a header for the bike I think. I'll just need to make a midpipe, cone and baffle for it.

[bwaller]

What brand of pipe do you have to work with the 650 head? You can be creative making a midpipe. I have used both old swimming pool ladder siderails (2" OD) and "milk pipe" from a dairy (2" ID). Both thin walled stainless steel. The pool ladder rails have great corners to cut & weld together. Milk pipe have various elbows available to cut & do the same.

Be careful of tight squish values. The last race of my first season I revved higher on the straight to compensate for gearing and the pistons just kissed the head. Just enough to clean the crown in similar spots on each piston. There had been adequate clearance. In talking to Mike Rieck the only explanation is that this was due to rod stretch. I now run even tighter clearances but with Carillo rods. I have machined the piston squish angle a couple times to hopefully work most efficiently, plus worked individual combustion chambers by hand to try to even squish values around the circumference.  I measure in 8 spots and have between 0.030 to 0.034". I'm pretty sure TG ran very tight clearance in his too.

[DavePhipps]

Here's my odd header that came with the 500. It fits the 500 perfectly but there seems to be more clearance underneath like it's made for a deeper sump. The tubes are a larger diameter but the inlets are butted so the inlet ID is the same as the 500. The PO cut it off at the end of the collector.

That's a cb500/550 Mac on the left.
I'll probably go cone engineering for the pipes. I don't have a pool and the local dairy closed decades ago. I miss that place. Great chocolate milk.

[turboguzzi]

around 035 in my bikes.
over 045-050 squish stops doing much,

but until you have both head and pistons in your hands, it'll be hard to do much planning.  it's not just the distance but also the amount of area in the piston that can be regarded as squish. inform your self by reading on two stroke squish bands first, easier to grasp the concept there.