Topic: CB550 Track Bike Goes Racing

[Rocketman]

After Road America I was looking forward to Mid-Ohio.  My Avon R2 rear was scorched, so swapped it out for a AM 23 medium compound rear.  It was a step in the wrong direction for my CB550 as I struggled with traction in practice.  GP 500 was the first race Saturday.  On the warm up lap I had a big slide so decided to take it easy the first lap.  Got a good start and charged into turn 1 only to be high sided into the next County.  When I landed I saw the bike make 2 barrel rolls before it stopped.  Ended up with 2 broken ribs and various sprains/strains.  Later that week I heard from SOHC member Scott M, who was in the same race, that my bike was smoking on the grid.  An inspection of the engine revealed the starter motor plug was missing.  I had crashed in my own oil.  Thankfully no one else went down.  I had depended on the O-ring to retain the plug.  What a bone headed mistake on my part.  The plug is now retained by a set screw.   



Besides healing the next 2 months were spent on repairs as only the frame, carburetors, and wheels had no damage.  The last piece was the tank and it was finished the week before Barber.  Also upgraded was the Grimeca front brake with Ferodo racing compound on the shoes by Michael Morse at Vintage Brake. http://www.vintagebrake.com/  New Avon's went on, a AM26 front and a AM22 rear.  I am not convinced my Honda has the HP or frame to run the conventional AM23 Cantilever rear. 

Since I retired in June we made the 12 hour trip to Barber on Tuesday to be there for move in day to the pits on Wednesday.  This is AHRMA's biggest race with over 600 entries and probably 300 competitors.  Everyone is assigned a time and a pit spot.  After move in we teched the bikes and were ready for practice on Thursday and Friday.  There is no practice on Saturday and Sunday.  In an effort to reduce confusion my plan was to practice the Honda on Thursday and Suzuki on Friday.  Practice on Thursday went well.  The tires were sticking great and the front brake just kept improving as the shoes bedded in.  Friday's practice on the Suzuki started out on a sour note as I forgot to turn the gas on and ran out at the Museum Curve.  Could not reach the petcock before I rolled to a stop.  I jumped off, turned the gas on, and as I was on the opposite side of the corner's race line tried to push start it with no luck.  A couple of laps later the session was red flagged and the crash truck took me directly to the race director.  He was none to happy with my attempt to push start on a hot track.  I just kept my mouth shut as I could tell he was one unhappy person.  Later as I read Nick Ienatsch's account of Barber I learned he had done the same thing in an earlier practice which explained the race director's statement I was the second person to make the same mistake.  Lesson learned.  http://www.cycleworld.com/barber-ahrma-vintage-festival-on-spondon-framed-yamaha-tz750  My lap times for the Honda were marginally better than last year as I was riding tentatively.  Suffering from the 'I crashed in my last race and was not going to do so 2 races in a row'.

The races went well and I finished 5th and 4th on the Honda and 9th and 7th on the Suzuki.  Chris Spargo on a RD that could spank a lot of TZ's won both Formula 500 races and Nick Ienatsch won both Open Two Stroke races on a TZ750.  My post race routine includes dropping the oil pan to check for debris.  Much to my surprise I found part of the cam chain tensioner!  This seems to be a known weak spot of CB550's that are raced.  Currently researching options on what to replace it with. 



Both bikes are on the lifts for the off season tear downs.  First race in 2017 will probably be Road America in June.  Planning to add Mosport in August for the VRRA's big race to my schedule.  Also looking at taking the Suzuki to Phillip Island in 2018.  It would be a once in a lifetime trip.  Will see if the budget will allow.

Here are some race, paddock, and Barber Museum photos.  It is a must see and a visit is highly recommended.



Practice on the CB550





Start of one of the races.  Race winner Chris Spargo on #19.



Practicing on the Suzuki RGB500



Nice CB350 in the Paddock





My brother's CB125



Barber Museum









CB450 Factory Racer



Kawasaki H1R Road Racer





Patton Road Racer.  John McGuinness won the IOM Classic race on a replica.



Kawasaki 250 Road racer



Honda Production Road Racer



Triumph Racers

[bwaller]

Thanks for the pics Martin, can't ever get enough racing pictures. You had me chuckling about the bump start efforts. Those competition coordinators have no sense of humour huh? Good write up, it all sounds familiar, especially that coming back from a crash part!

Chris is indeed a fast guy, but his bike is a rocket. You're right it's as fast as most good TZ's and that's saying something! It's not often I see someone disappear so quickly from mine up the straight at Mosport.  Nice guy, fun to race with.

It's good to read you have plans. I'll get you news on a camchain tensioner soon.

[Rocketman]

The first two events of the year are in the books.  I had planned an upgrade to higher compression pistons and hotter cam over the winter.  When I tore the motor down I found the head had been damaged and would need replaced too.  It is only money, right?     Mike Rieck came through with one of his outstanding port and valve jobs to get me back on the track.  The dyno confirmed the wisdom of using Mr. Rieck when the motor made 60 HP.  A 20% increase from last years 49 HP!  Off to the races.

Road America with AHRMA was first.  The Honda ran great all weekend and I scored two 3rds in Formula 500.  The competition was Ryan Hunt and Dave Morrow on their Yamaha twins.  My lap times were significantly better than last year and as well as the bike was running, they both out rode me.  Also pulled my RGB500 Suzuki out for the first time in 30 years and had a go on it too.  Finished 2nd behind Dave Crussell on his TZ750 both days.  Here are some photos.

Road America Pits

Found a video taken from Dave Morrow's Yamaha.  Was looking good until I overshot the turn at the end of the back straight.     Race starts at 5:30.  Ryan Hunt is #76 on the Yamaha and 309 is Tim Joyce on a 500GP single (Norton I think).  Counting the days to first race of 2017!

Found some footage from Sunday's race.

[RAFster122s]

Way cool Rocketman...bet you are itching to be back out there on the track, heck...even riding this time of year would be great.  Spring can't come quick enough to the nasty weather areas of the US that have kept bikes off the road for all the riders out there, especially those who get the mental health boost from riding.

David

[GV1390]

Man, this is cool! I'm visiting the Barber Museum this summer....heard it's majestic!

Good luck this season.

[Rocketman]

After the last race of 2016 I found that the cam chain tensioner had failed again. 



Fortunately for me, Brent Waller had tested a Benelli tensioner during the year with promising results.  Rather than keep replacing tensioners on what had become a regular basis, I followed Brent's lead and installed a Benelli tensioner in my engine.  I sourced it from the Benelli Bauer Shop out of Germany http://www.benelli-bauer.com/ .  It is listed as a "Chain Stretcher" part number 61058200.  To work in a 550 engine both the tensioner and upper engine case need to be modified.  The lower nut welded to the tensioner needs to be moved to match the hole in the cylinder block.  A small relief in the upper engine case needs to be ground so that the new tensioner is vertical.



New tensioner with lower nut already relocated.  I used some steel bar stock that fit within the tensioner and drilled then tapped the new mounting hole.



Tensioner before modification.  The nut in the middle of the tensioner needs relocated.



Small relief ground into upper engine case.



New tensioner in place.

With my cam chain tensioner issue potentially solved it was time to go racing.  The year started off for me at Road America with AHRMA.  Unfortunately I was still not up to speed from my crash at Mid-Ohio.  Even though I was 4 seconds off my lap times from last year I Managed a 2nd pace in Formula 500 on Saturday and 1st on Sunday.  Also raced my Suzuki 500 to a 2nd and 3rd place. 

Mid-Ohio Vintage Days (AMA/WERA) was next and I finally got my head back into the game.  Entered both Formula 500 and Vintage 3.  Finished 3rd in Formula 500 both days behind SOHC Forum Member Scott MacKenzie and Mark Morrow on a RD400.  Took a 4th and 3rd in Vintage 3.  Lowered my best lap times by 3 1/2 seconds. 

The big 50th Canadian GP festival at Mosport was next.  A detailed report and pictures can be found here http://forums.sohc4.net/index.php/topic,167793.0.html .  It was a fantastic event and the racing went well for me.  Managed a 3rd on both the Honda in P3 Middleweight and Suzuki in Vintage Heavyweight.  Mosport is now one of my favorite tracks and on my must race list.

Last race of the year was Barber with AHRMA.  A detailed report and pictures can be found here http://forums.sohc4.net/index.php/topic,168774.0.html.  Had a great race on Saturday and finished 5th in a race won by Brent Waller's son Tyler.  Lowered my lap times by nearly 4 seconds.  Also raced Formula 750 where I had my only mechanical of the year.  Lost power on the 3rd lap and DNF.  On inspection the hot wire to the 2/3 coil had failed.  Sunday was a washout due to Hurricane Nate.

Today I tore down the top end of the Honda to see how the Benelli cam chain tensioner had held up.  It was good news.  The wearing surface has minimal wear and is good for another season of racing.  Also found the pistons and head to be looking good.  The squish area of the pistons is clean and I am expecting all to be in good order after the carbon is soda blasted.



No noticeable wear to the Benelli cam chain tensioner.



Pistons and cylinder head looking good.

Planning to install a poor man's close ratio gear box this winter with a new 1st and 5th gear set from Moore Performance Engineering.  Also really close to that full fairing.  The mold will need modified so that a windscreen fits properly.



 Looking forward to 2018 and seeing every one at the races.

[RAFster122s]

Very Cool!  Thanks for the detailed report and very clear photos.  Congrats on some nice finishes and a successful racing season.  Glad you are all healed up from Mid-Ohio.

David

[bwaller]

Good wrap up Martin. Also glad to see the Honda held up well. I'm impressed with this engine, simple "tweaks" make large improvements allowing it to still be reliable considering doubling power output.

Have a Merry Christmas and Happy Philip Island!!

[MRieck]

 Martin...Looks like the engine is running very well and you have solved some of those 550 mechanical problems that come with roadracing. That is a great combination! It always inspires confidence and drive to get back out on the track. Time to squeeze a few more HP out of the engine going forward.
Mike

[turboguzzi]

tnxs for the update, and all looks good inisde.

check well your tranny gears, mine had a cracked dog.... as well as the forks, they wear out badly

maybe switch to straighter manifolds instead to the original S-shaped ones? free power in there

may i ask you where's the MLS head gasket from and cost?

[Rocketman]

I source the head and base gaskets from Dynoman.  http://www.dynoman.net/engine/index.html  They are made by Cometic.  http://www.cometic.com/ Have had excellent results with both.

Thanks to all who post on the forum.  In particular big thanks to Brent for sharing his CB550 knowledge and Mike for his most excellent head work.  Without them it would have been a much slower and more difficult build.

[MRieck]

tnxs for the update, and all looks good inisde.

check well your tranny gears, mine had a cracked dog.... as well as the forks, they wear out badly

maybe switch to straighter manifolds instead to the original S-shaped ones? free power in there

may i ask you where's the MLS head gasket from and cost?

That is good advice.

[Yamahawk]

Martin,
   I remember you at Mid-Ohio the last few years, the Honda is looking very good! I'm the fellow with the RD350 painted white and red, with YAHWEH on the tank! Also the 1989 VTR250 Interceptor... Nice to see you here, I am building a 1971 CB750K1 for fun right now, and have some plans for porting those cylinders on the RD350. It should run pretty well next year, and , God Willing, I will see you there!
Charlie

[Rocketman]

Soda blasted the carbon off the piston and head this morning.  Found some minor pitting.  On the pistons it is extremely light.  The head is a little grainy, but again very light.  Found similar, but much heavier damage on my old head and pistons. 





Trying to figure out what is going on.  I have been using the "F" mark on the advancer to set ignition timing.  I did back the timing off after ruining the last head thinking it is detonation.  Since the damage is much lighter I may be on the correct track.  I do not use a degree wheel so can't confirm if the marks on the advancer are correct.  Pretty sure I can continue to use the head and pistons, just don't want it to get any worse.  Has anyone else seen similar damage?  What are you timing your spark at and are you using a degree wheel? 

[MRieck]

 That grainy appearance is probably due to running open velocity stacks. Small particles of dirt get in the cylinders and pock mark chambers and the top of pistons.
 I think this would be a good opportunity to smooth the domes with a fine Scotch Brite wheel or polishing wheel. Tape the sides of the pistons and HOLD ON TIGHTLY. A light bead blast to the entire piston (with the ring grooves taped over) is a good idea. After that I'd have the domes and skirts coated.
 You clean clean up the chambers by carefully using a blue cross buff with a mandrel (you need some junk valves in there to protect the seats/valve job). You have an OS intake valve so that makes it a little more tricky when it comes to a junk valve.

[Rocketman]

Thanks for your thoughts Mike.  Will need to investigate air cleaners.  Don't want to go through a head and pistons every year.

[bwaller]

Martin, forgot to mention in the pm that I do have a small 6" degree wheel for timing with a strobe but with the Suzuki ignition any original marks can't be used. I find the best timing on a dyno first then mark the plate/case for future reference. I check with a strobe against the degree wheel to know what the number actually is. What fuel and how tight is your squish clearance? Usually that 550 chamber helps avoid detonation. Mike may have a point about grit, but I would think it would show up more as skirt/bore scratching.

[MRieck]

 I see more skirt scratches/bore marks when fiber clutch plates break apart. I have seen similiar condition on my on parts after running individual K&N's on the street for several years.
 I don't know what type of ignition Martin is using but switching to something more modern would get away from that mechanical advance and have a more reliable advance curve. He should be packing all his timing in around 3500 RPM with about 36 to 38 total degrees given the small bore. Brent and Turbo are using the GSXR ignition which has proven to be a great performer and very reliable.

[bwaller]

Absolutely right again Mike, plus depending on which model ignition gets a built in rev limiter.

[Rocketman]

Sounds like a couple projects over the winter.     Took a closer look at the pistons and all are scored on the front/back thrust faces.



I think Mike is correct regarding dirt entering my open velocity stacks.  Not sure if these are salvageable or if new pistons is the way to go.  Have both glass bead and vapor blasting available.  Mike, what coating are you referring to?  Will also investigate options for a digital ignition with advance.  Sounds like GSXR is a proven alternative.

[Yamahawk]

Martin,
You can send those pistons to Line2Line coatings, give them your bore sizes, and they coat for zero clearance. There is a specific break in procedure they give you, and they wear in to correct clearance. Your pistons should be coat able like that, why don't you contact them and see what they say? It's about $35 per piston.
They have a testimony by a racer who uses this coating on his FZR400 racebike, and it really helps preserve the pistons and bores.
Charlie

[Rocketman]

Thanks for the tip Yamahawk!

[gschuld]

Swaintech does something similar with their PC-9 skirt coating.  Nice people to deal with a well.

George

[MRieck]

 I have used Swain Tech many times but Charlie's suggestion is good too. You can smooth the thrust surfaces on the skirts with some 400/600 wet dry paper, bead blast and than coat. As Charlie stated...it will build up the surface and tighten up skirt to bore a bit. Nice low friction surface. If you Nikasil the bores the friction is reduced further and your bores will really never wear out.....it is very hard stuff.

[scottly]

I have been using the "F" mark on the advancer to set ignition timing.  I did back the timing off after ruining the last head thinking it is detonation.  Since the damage is much lighter I may be on the correct track.  I do not use a degree wheel so can't confirm if the marks on the advancer are correct.

Be aware that some of the pins that locate the advancer are 3mm, while the hole it engages in the end of the crankshaft are 4mm, resulting in a fair amount of error.