Topic: Let's go roadracing...continuing saga

[bwaller]

Valve springs. I use Kibblewhite dual springs mostly because that's all I can find easily. R&D offer springs but I've heard poor results. My experience proves springs should be changed at least every season. On occasion I've seen a loss of 15lbs seat pressure after only three race weekends. So the point is change them often.

This off-season is a breeze, cylinder is being replated for new pistons/rings. Otherwise everything looks good including the new gear that held us up at the beginning of last year.

[turboguzzi]

Replated? Are those alu bores with nikasil?

[MRieck]

Valve springs. I use Kibblewhite dual springs mostly because that's all I can find easily. R&D offer springs but I've heard poor results. My experience proves springs should be changed at least every season. On occasion I've seen a loss of 15pds seat pressure after only three race weekends. So the point is change them often.

This off-season is a breeze, cylinder is being replated for new pistons/rings. Otherwise everything looks good including the new gear that held us up at the beginning of last year.

That is gospel.

[bwaller]

No TG, plated aluminum bores are illegal. However plating the cast liners is ok. Nikasyl yes.

Mike, this spring set has two race weekends and only needed thin shimming, so will re-use them. That last set of springs were odd and had sacked 1/8" compared to new. I remember they were labeled correctly but man they were junk in no time!

[bwaller]

I may need a different crank, and this is the only spare I have. I suspect this is water damage, but otherwise the surface is very smooth.

Can anyone suggest any issue not to use?

[Tintop]

I've seen worse damaged journals.  Place that I have used for both race & street cranks for decades should be able to help.  http://www.canadianchrome.com/  I'd just send them those pics with an inquiry Brent.  The fear I would have is that the 'rust' may have weakened the surface, and it might gaul under race heat/loads.

[Tintop]

No TG, plated aluminum bores are illegal. However plating the cast liners is ok. Nikasyl yes.

Mike, this spring set has two race weekends and only needed thin shimming, so will re-use them. That last set of springs were odd and had sacked 1/8" compared to new. I remember they were labeled correctly but man they were junk in no time!

Are you sure about that Brent?  Maybe the sidecar rules were slightly different, but my impression was 'internals were free', only the main castings needed to be stock externally.

[bwaller]

Hi Brian. These crank pics are a spare crank. I'll add pics of the other one from the bike later.

Yes I was told plated alloy bores are a no-no, at least in P1-P2 unless they were plated from original.

[simon#42]

must admit i would not be keen to use that , have you had a good look at it with a magnifying glass? 

[bwaller]

The good and bad of it all.....

Last off season I had to have a new 5th gear c/s made because there was "chipping" of one tooth face. (At this point the only OEM gearbox part left is the countershaft.) At the same time there was one tooth on the 16T mainshaft 1st gear which showed a slight chip missing as well. There was some piston skirt scoring last year that I expect may have been caused by this "chaff." I figured since 1st gear is the race start only gear and for putzing around the pits one little chip could be tolerated.

This year more piston scoring plus one crank rod journal was also damaged. This m/s 1st gear now has 6 teeth with damage (pic below) so will now need a new expensive mainshaft produced since that 1st gear is integral. Again I expect this material is to blame for damage, somehow before the oil filter catches it.

I'm not a metallurgist but am fairly certain the steel used to make these components was correct, but perhaps not the material hardening. Long story, not worth going further. This 6spd gearbox has been flawless and used under race conditions for several years, but two parts in as many years is discouraging.

I'm now thinking cryogenic and micropolish treatments are worth a look. It doesn't replace proper metal choices etc, but after a long discussion today with a race shop manager, I was enlightened.

Also I found another good used crank in the shop that I cleaned and polished that is off for balancing. Comparing with the crank used for the last 10 years it is evident looking at the primary chain gear/sprocket there is wear. I'll try to enlarge the pic below so the tooth edge comparison is evident. New bearings all around and we'll be good to go.

Next up....I received back the newly re-plated cylinder. Two problems here, one sleeve did not plate well, in fact it should have been seen from a mile away, but was somehow shipped back. Secondly both upper & lower gasket surfaces were bead blasted. I told them not to touch these but probably some young guy with a new job went to town anyway. So now I will send them a single sleeve to be bored and plated. My plan is to try to drop the sleeves, clean up both surfaces on a surface plate and re install the sleeves when I get that one back. More work than it should have been. Once finished new pistons, rings and pins will be assembled.

Quite a bit more work that expected this off season. Many new parts for no real gain.


 

[turboguzzi]

a bit odd brent... 1st gear sees so little use and nevertheless damaged like that? sure it does have the highest tooth loading due to being the smallest diameter, but still....

[bwaller]

I agree TG. And until a year ago it really ever only barely showed a footprint from its mate. No way I can ever re-use now.

[scottly]

Does the damage on the gear face appear to be etched, rather than worn? Material missing where nothing can reach below the surface, slight cavities?

[bwaller]

Definitely material missing.

[simon#42]

i think its a heat treatment problem . aprilia 250 gears have always done this . when i complained they asked how many had failed which of course was none as i always changed them as soon as they looked damaged . italian logic stated that as none had failed there was no problem !

[bwaller]

I feel it's heat treat too. Problem with my stuff is it's all one off. No calling the dealer!

[754]

 Brent , back to the spare crank.. I would call it stain.
 If you can find a tenths dial indicator, I would roll it around and check with that.. I mean ten thousants of an inch, .0001 per line. It will tell you if there is wear..

[bwaller]

I won't be using that one anyway Frank, but thanks. It had a broken bolt in the right end also.

[scottly]

Definitely material missing.

I've seen similar on VW lifters, which was finally attributed to lack of ZDDP in the oil...

[bwaller]

Have always used ZDDPLUS. Pretty sure it's a heat treat issue.

[RAFster122s]

Brent & Michael, what kind life can one expect from either OEM or K&White springs in a steet application (mileage ballpark number?)?  Racing stresses components and motors far faster than a street bike would since they spend most of their time at very high rpms pushing a motor to max perf and output which yields very hot temps on our air-cooled motors.
Thanks for fielding a little off topic question...not related directly to racing.

Any of what you are seeing in your race motor a thing to look for with a street motor that has around 30-35k miles?

Thanks!
David

[RAFster122s]

i think its a heat treatment problem . aprilia 250 gears have always done this . when i complained they asked how many had failed which of course was none as i always changed them as soon as they looked damaged . italian logic stated that as none had failed there was no problem !

The auto manufacturers here have adopted this same attitude about motors in new cars for past decade or more allowing them to call a new motor which is burning or leaking or consuming up to a quart or a bit more between oils changes!  That is with 7500-10k mile service intervals...not sure if any new cars have 3000 mile service intervals...

[bwaller]

David, I remember when I first started testing seat pressures that a used stock spring set (inner & outer) yielded about 42 lbs. so quite low. I wouldn't hesitate to recommend Kibblewhite springs and following their installed height should give 60-65 lbs. Naturally they will sag with time but not as much as OEM springs would be my best guess. Mike probably has more experience.

I highly recommend the ZDDPlus Zn additive. They recommend 4oz per oil change. I use only 2 oz but change oil after each weekend. In a used oil sample I sent to Blackstone labs, the Zn levels were right in the sweet spot according to them. I don't particularly believe in additives, except for this stuff.

[bwaller]

I'm laid up with a bum knee so thought I would post a few updates since the last time on here.

The 2020 race season was limited to one event in September but I was still waiting for a replacement mainshaft so my bike wasn't available. The deposit on this new shaft was made in Dec 2019 and I received it in October 2020! The delay was mostly Covid related so no more to say here. (Pic below). The issue with material chipping from teeth face I believe is with heat treating and we feel this shouldn't happen again. In speaking with smart people who should know...cryogenic treating of used gearbox parts probably wouldn't offer any protection, but that micro-polishing would certainly reduce friction. So I sent the gearbox, shift drum and various other bits for ISF polishing. (Pic below).

It all looks great but when I went to press on the shaft bearings, they were slightly loose. I was told by many people this would never happen....but it did. Perhaps the parts remained in the tumbler too long, not sure. So I used green Loctite and figure that will cure that.

The hard bits from that gear tooth scored the crank, pistons and sleeves. I polished up a new used, sent it to be balanced and installed all new crank and rod bearings.

I sent a cylinder to Millenium for replating and that was another fiasco which was eventually resolved, so new pistons, rings and bores to start 2021. I like to order my copper gaskets undersize and manually adjust bore size to closely match the sleeves. Then had to make up some new SS o-rings.

During the last couple races of 2019 we experimented with clutches, and ended up with a bit of a hybrid 550/650 clutch but used the CB650 primary gear  ratio which spins the clutch faster. This should be a positive change, but at this point I feel only offers a minor improvement for race launches. Time may tell.

George was ordering new CB750 (296mm) cast iron rotors so I jumped onto that (thanks buddy) and had a set made to 5.25mm thick. After much deliberation and talking to George and Matt here I settled on a pattern and drilled them on a rotary table. Matt has had some issues with rotor cupping and cracking after dimpling (not drilling) but I'm hoping the smaller bike with twin discs will help avoid those issues. I had to make new caliper brackets, but now at least have a spare set of disc rotors that can be installed fairly quickly. The rotors are 170 grams heavier than what we used previously. However the higher coefficient of friction of the cast iron combined with larger diameter will make a marked improvement in braking.  (pic below)

Tyler asked for shorter footpegs so will simply use hollow aluminum pegs that removes a few grams over what I made originally. These are cheap and made to break easily in a crash. I cut them shorter and re-welded. We use a modified Kawasaki brake lever.

So what's left to do? I need to order an OutEx tubless kit for the rear rim, install that, then mount a new rear tire. I am changing the rear brake caliper bracket to allow a pivot bearing, then will weld a tab on the frame for a new brake torque arm. This instead of the solid mount, and swingarm attached effort previously. Then change brake fluids and Bob's your uncle!

 







 

[simon#42]

you are right about cryogenic treatment . i know all about the theory of how it works but in practice it seems to be a waste of time . not a big fan of micro polishing either unless the gearbox is designed with this finish the shafts will always end up undersize . i think from memory mat went down this route with one of his gearboxes and it broke . check with him for the details  .
the discs should work well ,i doubt you have enough pad area to overheat and warp them with the small brembos . if anything they seem a bit over the top!  .  glad you have posted , its been quiet of late and its interesting to hear what people are doing .