sprocket ratio asssistance

wrote:

Dragbike Mike,
 Ive got about 3 passes in the 90+ mph range. I'm as green as one can get at this stage, as soon as the light turns green my brain turns to mush. I have been leaning more toward the clutch, it was a new trac king clutch with extra plate 9 passes ago. Think im going to pull it. I bought sprockets but my gut just keeps telling its not gearing. doing my best to learn to tuck down after launch. Have MUCH to learn. Thank you for your insight

Southpaw - just a few more random thoughts/words of encouragement:

1)  Give yourself credit - you're actually taking the time and going through the trouble of getting your bike to the track.  A lot of people "talk" about doing that, but very few follow through and actually do it as it is a lot of work.   Talk is cheap.
2)  Don't get yourself down if you're only running X-seconds in the quarter and your buddies are running 2 seconds quicker.  We all had to start somewhere (in my case it was a 400cc Yamaha 2-stroke twin - ran a blistering 14.77@89 on it's first pass).  Quicker E.T.'s will come with time.
3)  If you haven't done so already, start a racing notebook.  Date, time, weather conditions, track condition, carb jetting, clutch setup, launch rpm, shift rpm, etc.  Over time, you'll see trends.
4)  There is no such thing as "cheap" racing.  Try to set a realistic budget and race within that budget.  There are no shortcuts.  As the old saying goes, "speed costs - how fast do you want to go?"
5)  Beware - no matter how fast you're running, you'll always want to go faster.  It's human nature, I suppose.  The adrenaline rush must have something to do with it as it can be quite addictive. You have to temper the urge to go faster with item no. 4 listed above.
6)  Practice visualization to help reduce race day jitters.  That is, try to picture yourself sitting in the staging lanes, getting called to the line, doing your burnout, staging, launching, hitting your shift points, body positioning, and crossing the line into shut down area.  This will help tremendously come raceday.  Early on, it can be daunting, as you are finding out.  Over time, though, you'll find that everything almost becomes automatic.  This will allow your mind to focus on the task at hand - that is, winning races!
7)  Have fun!  At the end of the day, that's what it's all about, right!?

Mike






 

wrote:

Dragbike Mike,
 Ive got about 3 passes in the 90+ mph range. I'm as green as one can get at this stage, as soon as the light turns green my brain turns to mush. I have been leaning more toward the clutch, it was a new trac king clutch with extra plate 9 passes ago. Think im going to pull it. I bought sprockets but my gut just keeps telling its not gearing. doing my best to learn to tuck down after launch. Have MUCH to learn. Thank you for your insight

Hey Southpaw -  a few more thoughts regarding your motor and possible lost horsepower:

1)  Yes, pull the clutch as it's easy enough to do.  Look for glazing on the fibers.  If toasted the fiber plates might have that freshly roasted aroma - once you smell it you'll know what I mean.  And, if overheated, your steels might show bluish purple hot spots.  Also look for slight warpage of the steels.
2)  This might seem obvious, but check your carb slides to make sure that they're fully open at full throttle.
3)  A simple compression check might be in order.  Again, it's easy enough to do.
4) A leakdown test is really the gold standard, however.  You'll need a leakdown gauge and a pressure source and even with that, it can be tough to perform the test on a stock motor.  You have to be able to find and hold TDC on each cylinder while performing the test.  On a dragbike motor you have the remote starter nut on the snout of the crankshaft on which you can put your socket and breaker bar to manipulate the crank.  On a stock motor, you don't have that luxury.  

Hope this helps.

Mike
 

This won't help with the gearing, but maybe with the jitters.  www.dragtracker.com/app/practice-tree/

Having been involved in racing for some time, NEVER trust what your competitors tell you about their set-up. One guy I raced with actually went to the trouble to file/grind off the stamps in the sprocket indicating tooth count so he could enter his own (incorrect) number. 

Always keep 'em guessing.

I used to put the teeth number stamp on the rear sprocket to the inside on my bikes. If someone asked me what size sprocket I was running. I always told them what I was running plus or minus a tooth or so!!!!

The 250cc two stroke GP bike folks were the worst. Used to call it the "genuflecting blues"  The tuners would always have to tie one of their shoe laces and they just happen to stop and knee as close to the rear of your bike as possible so they could read the tooth count stamped numbers on your rear sprocket!!!!!

Never thought about restamping the tooth count on the sprocket. Good idea!!!!

Well I drained the oil and found way too much aluminum flakes. guess im done for the season. Time to pull the motor and start over.....

wrote:

Well I drained the oil and found way too much aluminum flakes. guess im done for the season. Time to pull the motor and start over.....

Don't throw in the towel just yet!  Pull that clutch and look for a broken fiber (friction) plate that might be disintegrating.  That would be the most likely source of aluminum particles in your oil.    If they're coming from somewhere else, then you might have some bigger issues and will have to dig deeper into that motor.

Mike

 

Ok i will pull it tonight and check

Nope it's not the clutch, it still looks new....ugh
 

Turns out to be the cam bearings. Cam and bearings are both destroyed. I replaced all the bearings. used assembly lube. proper torque. Got good oil pressure...what am I missing?

wrote:

Turns out to be the cam bearings. Cam and bearings are both destroyed. I replaced all the bearings. used assembly lube. proper torque. Got good oil pressure...what am I missing?

Im not an engine builder but possibly sealant around the outer rear cylinder studs. If you used APE studs I hear the trick is to enlarge the cylinder at those same stud locations. Theses bikes rely on oil volume not pressure.

Sealant not an issue as I don't use it on gasketed surfaces. I did use APE studs though, interesting....