Here is one that is wearing out what's left of my brain...
I have what started out as a D&D 1010 on an 03 900 Mountain Cat. The motor is hogged out, runs on last years weedwhacker gas, never detonates, has seen a ton of N2O go through... This sled has been bullet proof for 4 years. I decided to try for more this summer... I dropped and rolled the case, cryo'ed everything, put on 48mm Lectrons, I went with a Cutler TPS block and new TPS, had Jaws weld on slip fits to keep things cleaner, raised exhaust ports about .0080", etc (nothing else I could think of to call a variable).
Here's the problem:
She runs like a raped ape! But the motor won't spin past 7600rpm. And I know those pipes like 8000 to 8100. In the trailer with no belt...it won't hold past 7600, which is exactly where it is on a long hill or on a lake. I have adjusted the TPS a couple of different ways, but no better. The carbs are, I think, dialed in right where I need them. EGT's are close to 1200 when it's really climbing. I have thrown lighter weights at it - from 72.5g to 64g. It likes the 70g weights. Any variance from the 70's will cause it to drop R's. I put 72.5's in and it dropped to 7300. I put 67's in and it dropped to 7300. I have done the basics - changed springs, belts, plugs...I even changed out the stator and pick-up thinking the cryo process may have messed things up. The exhaust valves are leaking a little exhaust through the cables, but are travelling through the full range consistently. They are in correctly... (I have been idiot before!)
Here's what I'm thinking:
Could the bigger carbs be causing that much more air to go through the motor that the exhaust is creating a bottleneck? I am running Jaws D pipes with 39mm U-tubes going into my can. I talked to Greg and he thought the exhaust port change may be causing more heat in the pipes and suggested upsizing the U-tubes to 42mm. Before i cut my coated and polished can up to weld in new tubes, I wanted to ask for suggestions...
I am going to check the timing, but I can't think of how that could be messed up. I run a stock key and didn't touch the computer.
I sure would appreciate some input!!!!!!!!!!
Thanks,
Kor
I have what started out as a D&D 1010 on an 03 900 Mountain Cat. The motor is hogged out, runs on last years weedwhacker gas, never detonates, has seen a ton of N2O go through... This sled has been bullet proof for 4 years. I decided to try for more this summer... I dropped and rolled the case, cryo'ed everything, put on 48mm Lectrons, I went with a Cutler TPS block and new TPS, had Jaws weld on slip fits to keep things cleaner, raised exhaust ports about .0080", etc (nothing else I could think of to call a variable).
Here's the problem:
She runs like a raped ape! But the motor won't spin past 7600rpm. And I know those pipes like 8000 to 8100. In the trailer with no belt...it won't hold past 7600, which is exactly where it is on a long hill or on a lake. I have adjusted the TPS a couple of different ways, but no better. The carbs are, I think, dialed in right where I need them. EGT's are close to 1200 when it's really climbing. I have thrown lighter weights at it - from 72.5g to 64g. It likes the 70g weights. Any variance from the 70's will cause it to drop R's. I put 72.5's in and it dropped to 7300. I put 67's in and it dropped to 7300. I have done the basics - changed springs, belts, plugs...I even changed out the stator and pick-up thinking the cryo process may have messed things up. The exhaust valves are leaking a little exhaust through the cables, but are travelling through the full range consistently. They are in correctly... (I have been idiot before!)
Here's what I'm thinking:
Could the bigger carbs be causing that much more air to go through the motor that the exhaust is creating a bottleneck? I am running Jaws D pipes with 39mm U-tubes going into my can. I talked to Greg and he thought the exhaust port change may be causing more heat in the pipes and suggested upsizing the U-tubes to 42mm. Before i cut my coated and polished can up to weld in new tubes, I wanted to ask for suggestions...
I am going to check the timing, but I can't think of how that could be messed up. I run a stock key and didn't touch the computer.
I sure would appreciate some input!!!!!!!!!!
Thanks,
Kor
