My buddy has the HPD race mod. He says he is having trouble with the takeoff. From a dead stop it bogs down before it picks up and goes. From a rolling start he says it runs like crazy, but seems like the clutch is engaging at too low an RPM on take off, not up in the power.

He is running the blue spring now.
Any suggestions?

 

The blue spring should work fine. He might have a pilot jetting problem. Did it just start or is he tuning it in?

 

Is it a 400 or 250?

 

Its the 400, the complete HPD quad. The motor runs great, just seems like the RPMs should be higher on take off for better acceleration.

 

What weights is he running? I'm currently running the violet primary with the 10-56 weights and it runs awesome with great acceleration. But the blue should run really well with either the s55 or 10-56's. Check belt deflection too to see if maybe the belt is slipping on take off.

 

[img]i/expressions/face-icon-small-disgusted.gif[/img]Well I am the one with the quad. I know the clutch is not slipping. This is the problem. I am stopped, get ready to go, hit the throttle, anywhere, and it is not responsive for at least a couple seconds and then it is hold the #$%^ on! The quad has very little time on it and is 4 years old, with the original clutch springs. The pilot is 45, middle needle, 172 main PWK. Twin air, airbox, delta force, special race mod pipe for his chassis[HPD]. I even put the air mixture screw 3 full turns out to see if it was running rich, with no luck. I did talk with Shotwell and he said it could be compression, not the spring. Anybody else?

 

By the way, blue primary, 55 weights, kevlar belt, violet secondary? special snobile clutch helix. I really dont think it is the driven or secondary clutch. Either the primary spring is very weak, or I have lost compression, or the jetting is way too rich oin the piot to get out of the hole![img]i/expressions/face-icon-small-blush.gif[/img]

 

Sounds like it could be the reeds. Bad or worn reeds will do the same thing. The 250's have a lag from take off because they dont have reeds.

 

What carb are you running. I'm running the 39 pwk and have a 35 pilot at 2600 ft. elevation. It has great throttle response. I'd check the reeds too as 2many said. I guess you are just getting it back together?

 

Brand new reeds, delta force. 39 pwk.[img]i/expressions/face-icon-small-sad.gif[/img]