Need power coming on sooner

[mecheech]

We have an 07 DRX 50 W/C and it takes almost the whole straight way before the powerband kicks in, he is braking for the corner before getting into all the power, this is indoor MX.

It is really noticable when I lift the back end up before the start, it revs alot slower then the other bikes, and a few seconds later U can hear it then kick into the powerband.

It does have the OKO carb and I plan on switching to the Kehin 20mm. I also changed the front weights to 3 grams from 3.5 grams, my boy weighs 45lbs soaking wet. I am also going to switch to an 18 tooth front sprocket.

So hopefully with the new carb and sprocket I can get it to come on a little sooner. I always thought he was just not pushing the throttle all the way.

Thanxs in advance for any comments or advice.

[neveready]

Well the jetting would be the first place to start. These things are jetted really off from the factory at times. Also the OKO can be tricky. They seem to either run really good or really bad. You will have good results with the keihin, just make sure it is legal to change in your district or race governing body. If this is legal also use the UNI air filter and do away with the oil injection and premix in the tank.

Going with the heavier rollers actually makes it rev slower, you either need lighter rollers or heavier clutch springs. We run our L/C 50 bone stock with the new smaller sunworld carb. We run 3.3 rollers 1500clutch springs and a red mallossi comp spring, and we run really tight with the 70s in our class.

We try not to gear the 50 real low (19/32) unless the track is really small, we try to get our rpm out of clutching and gear for speed. Might not be right but it works well for us.

Their are alot of great people on here and some really great dealers as well. Keep reading and asking and you will get the info and parts you need.

[tireman43]

Sounds like you're on the right track. I would recommend going to 4.5g rollers though to give a little more weight/momentum for the clutch to engage. I could be wrong but there is a happy medium and 3g sounds pretty light. Other wise it sounds good. We went up a few teeth in the rear which is the same as going down in the front. It will help the bottem end and makes a huge difference on the short tracks with tighter turns.

Kevin

*EDIT* well it appears I can't type fast enough and neveready beat me to an answer which is different. I'm no clutching genious so he is probably right. I can help tell you what I run in our 90 mod but the 50 is just how it came and my little man is happy with it.:D

[mxdad423]

Sounds like it is between the pilot jet and the needle setting, thats where I would start.......How's the plug burning?

Kevin Smitley

www..net

[bulldogfallon]

Originally posted by neveready
We run our L/C 50 bone stock with the new smaller sunworld carb. We run 3.3 rollers 1500clutch springs and a red mallossi comp spring, and we run really tight with the 70s in our class.




That is a pretty heavy torque spring (Red Malossi 2k) in comparison to the roller weights you are running....

Does it have a lot of top speed? or just a lot of bottom end grunt? I bet your rider must keep the throttle pinned to make this work?

We have found that a white Malossi (1K)spring with 3.2 gram rollers lets it hit out of the hole well, but loses some top end speed.


I'll have to try that set up to see how it runs....Always willing to try a new set up....

[bulldogfallon]

Factory tranny set up is close so I would look at the jetting....

Do you know what jets are installed currently?

Sounds like it is rich to me...

[mecheech]

Thanxs for the replies.

We do have the injection removed and are running a UNI filter. As far as rules, there are non here in the great Northwest. We have to run against Cobra's and heavily modded DRR's and Kasea's.

That is where my inexperience and sometimes lack of time slow us down.

Les set up the OKO with the jetting most likely needed and I changed the weights to 3 grams but other then that and putting on a clean filter I have just let him race it and we are up to about 20 indoor mx moto's each about 4 mins or so.

I do have a feeling once we switch to the Kehin, smaller sprocket and maybe check into the KOSO silencer it will be all :D :D :D

Thanxs again for everyone input. Time to give Les a visit and see what he can help me with.

[mecheech]

Neveready thats some good air Ur boy is getting.
Jakie Boy is just starting to get the hang of getting the wheels off the ground and also not letting the front end drop, which probably would be easier once I get a little more throttle response.


http://i240.photobucket.com/albums/ff239/jakiesdad/image-4.jpg

[bulldogfallon]

Originally posted by mecheech
Thanxs for the replies.

We do have the injection removed and are running a UNI filter. As far as rules, there are non here in the great Northwest. We have to run against Cobra's and heavily modded DRR's and Kasea's.

That is where my inexperience and sometimes lack of time slow us down.

Les set up the OKO with the jetting most likely needed and I changed the weights to 3 grams but other then that and putting on a clean filter I have just let him race it and we are up to about 20 indoor mx moto's each about 4 mins or so.

I do have a feeling once we switch to the Kehin, smaller sprocket and maybe check into the KOSO silencer it will be all :D :D :D

Thanxs again for everyone input. Time to give Les a visit and see what he can help me with.


No rules?

Why not go for a Metrakit, Polini or Malossi 50cc kit then?

There is a guy that could make that 50 scream as long as you can alter the stock pipe....

There will be an article out soon about them....and what they did with all stock DRR parts (except for the pipe)

PM me if your interested in his info

[drr5]

this may sound weird but. if you have had your clutch cover off did you tear up the cover gasket and discard? if so you may be biding the clutch bell against the clutch cover we ran into this before. just a thought

[mecheech]

I still have the the gasket in place but when I tear into it this weekend I will look just for craps and smiles to make sure nothing looks to be rubbing or out of place. Thanxs.

[hotquads1]

your launch can be hindered by the 21mm carb , a smaller carb such as the 08' w/c 50 will help greatly when jetted spot on. but you can compensate with the clutching to fix the issue . You need the bike to leave the line in the " power band" , DRR has 2 different clutches and variators and they require a different set-up , so to guide you further we would need to know which you have. meanwhile a stiffer torque spring will be your best bet , just as the others have stated.
marc

[jetski_dawg]

this is a good thread.. i have the same issue with a w/c50 08 with the sunworld carb (all settings from factory).. it seems it bogs at the start but when it hits the powerband it comes on strong..the plug looks good so i was wondering if i should start with the weights and springs or leave it alone...thanks

[hotquads1]

jetski dawg ,
I can put you right on , there are a couple of changes that need to be made , I cannot write the whole set-up ,but if you contact me I will be glad to help you.
marc

[jetski_dawg]

thanks marc!! ill give ya a call

[jetski_dawg]

hey marc.. i installed your kit last night and i could tell a big difference with the holeshot..much better.. ill let you know how my son does on it this weekends race...thanks again

[hotquads1]

Thought that might perk it up ! Glad to help ,
marc

[#404's Dad]

Great thread!! So am i understanding this correctly that you guys are liking this little SunWorld carburetor on the 50cc bikes?

How does it compare to the PE 20 ? Hell I tossed both of ours in a box brand new off the bikes figuring that little booger was nothing more than a little booger lol, Maybe I should try one out on the track and on the Dyno.


Corey

[quadscrib]

Would someone be willing to breifly explain what lighter/heavier clutch springs do and like wise w/ the torque spring?
I totally get the roller deal but the springs slightly (alot) confuse me.... Also whats the stock roller weight on 08 Drx50, or spring wieghts for that matter so I can understand where Im going from stock.
Do you guys use a scale to wiegh the rollers or just keep track of whats what?

[hotquads1]

The clutch "shoe" springs (3) , control the force which allows the shoes to engage the bell , the stronger the spring the higher the rpm when shoes engage clutch bell. The torque spring is the force that determines at what point the rollers will start to move the frnt variator , shifting the belt up and down. the roller weight and torque spring strenth are relative to each other. the higher the torque spring strength the more roller weight force it will take to move the belt, roller weight force is generated by centrifugal force which is increased with rpm . heavier roller weights create more force at a lower rpm , requiring a dialing in process for most engines to find the best shift point. yes we postal scales to weigh and verify rollers.
marc

[#404's Dad]

Originally posted by hotquads1
The clutch "shoe" springs (3) , control the force which allows the shoes to engage the bell , the stronger the spring the higher the rpm when shoes engage clutch bell. The torque spring is the force that determines at what point the rollers will start to move the frnt variator , shifting the belt up and down. the roller weight and torque spring strenth are relative to each other. the higher the torque spring strength the more roller weight force it will take to move the belt, roller weight force is generated by centrifugal force which is increased with rpm . heavier roller weights create more force at a lower rpm , requiring a dialing in process for most engines to find the best shift point. yes we postal scales to weigh and verify rollers.
marc

That is the best I have heard that explained yet Marc, that should REALLY help some folks out allot :thumbs up:

[quadscrib]

DITTO! Thanx Marc!