need the holeshot

[kfx450]

we are at round 10 of our series and we need a holeshot. We are running a totaly stock drr50 with a fresh set of 2000 shoe springs white koso main spring and 3.5 rollers. This bike is horible off the line. has been all year but we are looking for a good finish to build off of for next year. We can run with anyone but are normally toward the end off the line as the bike just dosnt pull well of the line but pulls great once you get it rolling.

I am looking for all suggestions. I am guessing the clutching could be better but not sure. Give me everything you got from mild to wild. race is next saturday.

thank you
jayme

[mudder700]

50's are very finicky, make sure your air screw is adjusted right, that will help a ton, we had 1000 engaugement springs...the air screw adjustment is critical and will really improve performance off the line as it affects throttle response alot

[hardingsfamily]

Make sure you have a fresh top end. That was my biggest problem when i was facing the same issues. Check the compression.

[DAVYS DAD]

IMO gear it down to get a better holeshot. weigh the options do you need all your top end speed or could you use a little more acceleration from turn to turn and jump to jump this may help or may hurt but its worth a try. Hope you get it figured out and GRAB some holeshots.



later

[kfx450]

Alright we got some numbers for ya so you can give me more suggestions.

compression 120-130 depending on gauge

air screw 3 1/2 set with tach

belt starts moving at 6000rpm clutch engages at 6600-6800 revs imediatly to over 7000 once starts engaging. (need to fix this problem first is my guess, I have alot of clutch parts new shoe springs from 1000, 1500, and 2000. also have 3.5 and 4.5 gram rollers and a 1500 ztr spring give me your suggestions)

koso white spring which is supposed to be 1000

21mm pwk keihin will have to check the jets as I havn't had them out in a while.

[drr5]

imo time for a top end but still not bad numbers , if your motor is stock you really need to get the carb tunned just right we ran the 50 class for a good while ,no hole shots till we dialed in the carb but as mudder stated 50s are finicky and everything should be done in very small increments. time consuming yes but watching your son or daughter holeshot the pack priceless. after reading your post again noticed the carb size we had the 19mm stock carb but this carb will get the job done also easier to find jets for

[bulldogfallon]

Originally posted by kfx450
Alright we got some numbers for ya so you can give me more suggestions.

compression 120-130 depending on gauge

air screw 3 1/2 set with tach

belt starts moving at 6000rpm clutch engages at 6600-6800 revs imediatly to over 7000 once starts engaging. (need to fix this problem first is my guess, I have alot of clutch parts new shoe springs from 1000, 1500, and 2000. also have 3.5 and 4.5 gram rollers and a 1500 ztr spring give me your suggestions)

koso white spring which is supposed to be 1000

21mm pwk keihin will have to check the jets as I havn't had them out in a while.


The small 16mm carb is ideal for holeshots...if this is in your budget I would strongly suggest it....I wouldn't run a 50 w/o it..

Converted 3 setups like this in the last few weeks and all have made great comments back to me for making the change...big difference!!

If the Koso spring is fresh....I bet the mix of the 3.5 and 4.0s would work well...

Try the 1,500 shoe springs to see if that helps...you may need the 1,000 shoe springs to bring the clutch engagement down even more.

Air screw leads me to believe that your pilot is way rich.....probably should be in the 40 to 42 range if it is a Keihen PE 20 or PWK21 copy

[kfx450]

can I order a sunworld from you setup close to what we need. and how much?

I have a stock carb off of an older alpha sport 50, is this what I am looking for?

The carb that is on it is a 21mm keihin not a knock off. I had problems with the bike and thought it was the stock carb so I changed it out with a 21mm keihin I had bought from hetrick that was on another bike.

clutch spring only has a couple of rides on it.

What should the compression number be on a stock 09 50?

I have access to a dyno to set up the jetting but what should the air fuel ratio number be. I know you should do it by looking at the plug but being new to this I wasn't sure if this would be more accurate or just a hassle?

thank you
jayme

[kfx450]

I also have a hetrick pipe and silencer laying around would this help the 50 or hurt.

jayme

[redonkulousruntsracing]

KFX....

Your problem is the 2000 rpm shoe springs. I guarantee it!!!
I chased the same problem for weeks. My kids Apex 50 did the exact same thing, with the 2000 springs, the belt was 3/4"-1" in to the rear pulley before the shoes would actually engage just like taking off in 2nd or 3rd on a 450 quad. We lost many races due to bad holeshots. If he would roll out 10 feet and the punch it, it would tear the tires loose, but fron a dead stop, it would just roll out of the start gate. I put 1500 rpm Koso's in it and instantly notice the difference. Night and day difference!!

Also, the stock carb should be a 16mm, that 21 is way too big, big carb = high rpm power, little carb = low end power.

[kfx450]

okay I changed the shoe springs to 1500 and went from more than half an inch to about a 1/4 inch. went to 1000 and now we are down to about an 1/8 inch before shoes engage. will push through the rear brakes now so we should be in alot better shape. still moving the belt at 6000 but shoes are engaging around 6200 initialy but will come in sooner after initial hit.

I tried a 1500 ztr spring but the 3.5 gram rollers wouldn't move it. Has anyone else had problems with ztr springs in a 50 clutch. this spring was in a 09 90 and worked fine but will not go in the holder right on a 09 50. it wants to stick in its holder cause lots of friction and tries to twist the spring. I had this same problem with a 1000 ztr spring.

09 drr50 now comes with a 21mm carb.

jayme

[bulldogfallon]

The small carb is an option too...it will be back on the 2010s.......WAY BETTER CARB!! IMO


Most guys use

Yelllow Malossi w 3.25 to 3.5 gram rollers
or
Red Malossi w/3.75 gram rollers

You can't compare the torque spring ratings by RPM across brands....not even close to matching


Get a red malossi torque spring with 3.75 gram rollers and a 782 belt and you will be good to go.....

This belt will also allow the belt to sit lower in the front and higher on the rear pulley....the 780 belt is just a touch short IMO

Carb change is obviously recomended if rules allows...it was an offered carb in 2009....but most came with 21mm

[redonkulousruntsracing]

I also tried the ZTR 1500 and I tried up to 4.25g rollers and I couldnt get it to shift out, probably would with heavier rollers, so I went back to the red Malossi and the my 3g rollers and it's perfect. Anything I learned from wrenching on 90's last season I had to forget for my sons 50.

[kfx450]

With the clutch better, the bike seems to be much quicker. This bike will now keep digging on a steep hill instead of just falling on its face and sitting still.

[bulldogfallon]

Thats because it is taking off in low gear....

50s need low gear...without it they are doomed

[kfx450]

thank you guys for all your help. We ended up 3rd off of the hole shot and stayed there for 3rd on the day. We stayed with the leaders and that group left the everyone else laping most of them in the 30min race.