Cam angle for drag racing

[machz69]

I know it's been asked a 1000 times but never get any answers? It seems anyone with a turbo yamaha is very tight lipped? I have a 55* cam right now and it seems to pull pretty hard but just wondering if this is close to what a yamaha likes or is it out to lunch?

 

[tjc]

Pm? we are all interested in the answer, haha.

Just giving you a hard time. But I am interested.

 

[mbarryracing]

Dave,

Helix for a turbo is tough because it depends on how fast your boost comes on and how much... have to try to hold it back from over-revving.
Do you make boost super fast? What type profile weights? Are your primary weights notched? Are you coming off the line on a 2-step stutter?
Also depends on the surface your running on for the load.
Loose snow, grass, ice? Deep lug track? chisel studs? gearing?

I would be willing to share what my particular setup likes best for a helix and spring,PM me, but again each setup and sled is different depending on different variables. No one magic answer, but 55 seems like your not going to get enough belt pressure and results in belt slippage / hot clutches?

 

[machz69]

Dave,

Helix for a turbo is tough because it depends on how fast your boost comes on and how much... have to try to hold it back from over-revving.
Do you make boost super fast? What type profile weights? Are your primary weights notched? Are you coming off the line on a 2-step stutter?
Also depends on the surface your running on for the load.
Loose snow, grass, ice? Deep lug track? chisel studs? gearing?

I would be willing to share what my particular setup likes best for a helix and spring,PM me, but again each setup and sled is different depending on different variables. No one magic answer, but 55 seems like your not going to get enough belt pressure and results in belt slippage / hot clutches?

..Lol.. I'm not asking for anyone's secret recipe, I know people do test and won't give their set ups but just more of ball park/starting point. That's the thing, I don't really know what a yamaha standard type starting point is. Yeah for sure my clutches are getting warm... too warm..
I know that with a trubo sled h.p. can be all over the place, but there has to be a gear set that would be pretty much the normal starting point?. I read a lot of posts on this forum but I never see anyone givinf anyone a set up to try?.. when I ran Bomb, You can get 10 different set ups in a bomb forum in about 1 day?.. It don't mean they will all work but it give's you an idea really about the direction to head to... Once I get a good set up that I'm happy with on my sled I will be more then happy to try and help others. I won't give up my exact set up but...hahaha

 

[kviper]

A 55 may be ok but the more cam you have the more driven spring you will need. Start hunting for stronger driven spring's, compression and wind until your clutches are cool then dial in shift RPM.

 

[machz69]

A 55 may be ok but the more cam you have the more driven spring you will need. Start hunting for stronger driven spring's, compression and wind until your clutches are cool then dial in shift RPM.

I have the purple EPI spring, I'm not even sure what the tension is for that spring?.. still learing the yamaha clutching.. I was also thiking of getting away from the yamaha belt for drag racing?.. maybe something softer. also the gearing not sure if that is close.. 23-38 Don't get me wrong the machine is pulling hard but I know it has a LOT more in it. This is just the first set up I through at it and I know it's not the best, the clutches are pretty hot.

 

[mbarryracing]

Sent a PM.
For gearing depends on how long of a distance are you racing and what MPH you are trying to run. Like any drag racing...

 

[machz69]

snow drags 660'

 

[Stigapex]

snow drags 660'

Hello

I'm also trying to find the perfect setup for snowdrag 660,
2011 Apex XTX, MCX 290

Track 1,75" Backcountry
gear 22/37
Ulmer Helix seems like 55/48

The OEM Yamaha belt is very hard, and I must drive the sled very hard before I can start in any drag, so the belt becomes warmer and a little
softer. When the belt is warm, I think the sled drive well in 660. With a cold belt to much hesitation in acceleration.

I thought of changing the spring(white) pressure in secondary from 6-1 to 6-3. I thought this will give me more belt-pressure, but will this effect badly in mid-register?

 

[machz69]

How do you find the gearing?.. what kind of mph are you getting in 660'

 

[Stigapex]

How do you find the gearing?.. what kind of mph are you getting in 660'

I'm not driving any drag competition, so I don't have any perfect times and speed. But we use to line up 660 ft, to see who wins, and what kind of speed we will reach. In good condition GPS speed 110 MPH.

To find the gearing. First 24/37, then testing against another Turbo-sled. The 24/37 gearing, to slow in mid register (150-450 ft), then testing 23/37, same thing, to slow in mid register. Then testing 22/37, better. then testing 21/37. When driving 21/37 I think the sled didn't become any better in 660ft then the 22/37, so I went back to the 22/37.

You see, sometimes we drive a little longer, maybe a 1000-1320ft race, and then I don't want to be to low in gearing, but I've heard that someone uses a lot lower gearing for 660ft races, and that is also sleds with more power.

 

[machz69]

Yeah I have been thinking about going to 23/39.. this would be just for 660' drags. I'm looking to be around 110-112 mph. I'm very interested in seeing what others are running, not that I'm trying to know what your set up is but just more to get my mind around what these big 4 strokes like.

 

[Stigapex]

Hello again

The toughts is in wintertime allready, so my next step is to change sprockets to 21-39 or 20-39.
Will also order a MSD launch-control, and then I need some higher RPM before takeoff.
What spring in primary will give me enough RPM, but not to hard in end-pressure?