bajardine
New member
I've been trying to dial in my Viper after putting a set of SRX 600 heads on it. I opened up the heads to the 700 bore and then shaved off about 20 thou from the heads since I'm using the Viper head gasket. The previous owner had the stock head opened up to 24 CC on all domes. At my elevation (4500 ft) that head was only reading 100 PSI on my compression tester. After putting on the SRX 600 heads, I was seeing 120 PSI across all cylinders. I put all new piston rings in the engine while I was at it and with my homemade leakdown tester all cylinders were reading about 96%.
Here's my problem: I'm not making the power I should be. I've dialed in my clutching to hit 88-8900 RPM at the elevation I ride and my weights are way too light. I have a set of 8CH weights in the clutch that are 4.4 grams lighter than the 8DN-10's that I should be running according to SLP since I have their triple pipes on the sled. SLP recommends that I should also have another 3.1g rivet in the first hole so I'm running 7.5g lighter weights total.
What could cause me to be losing so much power? When I get on my brother's '01 MM 700, it has noticeably a good deal more power than my Viper and far out climbs my Viper on any hill. His track speed is a lot higher too. We both have 151 inch tracks on our sleds.
Could improper timing be an issue? Where else might I be losing so much top end performance? I suspected the power valves but they've been cleaned and adjusted. I was actually disappointed when I tore into them and found that they were actually almost perfectly adjusted since I was looking for a culprit to blame.
Thanks,
Bruce
Here's my problem: I'm not making the power I should be. I've dialed in my clutching to hit 88-8900 RPM at the elevation I ride and my weights are way too light. I have a set of 8CH weights in the clutch that are 4.4 grams lighter than the 8DN-10's that I should be running according to SLP since I have their triple pipes on the sled. SLP recommends that I should also have another 3.1g rivet in the first hole so I'm running 7.5g lighter weights total.
What could cause me to be losing so much power? When I get on my brother's '01 MM 700, it has noticeably a good deal more power than my Viper and far out climbs my Viper on any hill. His track speed is a lot higher too. We both have 151 inch tracks on our sleds.
Could improper timing be an issue? Where else might I be losing so much top end performance? I suspected the power valves but they've been cleaned and adjusted. I was actually disappointed when I tore into them and found that they were actually almost perfectly adjusted since I was looking for a culprit to blame.
Thanks,
Bruce
whats the squish clearance?
mattyg1405
New member
i am no clutching expert at all but:
what are you running in the 8ch for rivits?
whats the total weight?
how did you get it to spin what you want for rpms? without tuning the weights?
maybe your clutch setup is hindering performance severely ???
what are you running in the 8ch for rivits?
whats the total weight?
how did you get it to spin what you want for rpms? without tuning the weights?
maybe your clutch setup is hindering performance severely ???
bajardine
New member
The squish clearance I have is between .055-.06 varying a few thousandths between sides and cylinders.
It's a Mtn Viper but when I got into the clutch it had 8EK weights that were originally in the regular Viper. After I got the heads done and running I could only get 85-8600 RPMs with the y-w-y spring. I tried the same weights with the g-w-g hoping it would raise my shift RPM but it only affected my engagement RPM and raised it above 5000 RPM. I had a set of 8CH weights that weigh 35.32 grams each. With these weights and the y-w-y spring I hit 88-8900 RPMs at my riding elevation of 7000 ft. According to SLP I should have in a set of 8DN-10s plus a 13.3 mm rivet which combined is almost 7 grams more than what I have in there. That's why I'm thinking I'm not making the power I should be.
Any ideas?
It's a Mtn Viper but when I got into the clutch it had 8EK weights that were originally in the regular Viper. After I got the heads done and running I could only get 85-8600 RPMs with the y-w-y spring. I tried the same weights with the g-w-g hoping it would raise my shift RPM but it only affected my engagement RPM and raised it above 5000 RPM. I had a set of 8CH weights that weigh 35.32 grams each. With these weights and the y-w-y spring I hit 88-8900 RPMs at my riding elevation of 7000 ft. According to SLP I should have in a set of 8DN-10s plus a 13.3 mm rivet which combined is almost 7 grams more than what I have in there. That's why I'm thinking I'm not making the power I should be.
Any ideas?
bajardine said:
So are you hitting the RPMS you want? Is it just clutching then you need to figure out?
bajardine
New member
No, I think the clutching is on for what my engine is doing now. I am hitting where I should be at 88-8900 RPMs. I just should be making more power and turning heavier weights. My brother's '01 MM 700 is pulling a lot harder and out climbing me everywhere.
What are the details of your secondary? What are clutch temps after riding?
squish would be ok, so reading over your post, whats the jetting in the sled?, have you looked at piston wash?. I agree with your idea its not clutching, your not making power.
bajardine
New member
Right now I have the secondary set with the green spring at 80*.
The main jets are PTO 152.5 and 150 for both center and mag. I ride around 6-8000 ft and latelty it has been between 20-36*F. I was considering leaning the mains one step. I haven't gotten to reading the piston wash just yet but the plugs have been chocolate brown with a reddish tint.
The clutch temps are higher than I would like. After a long pull on a big hill when I put my hand on the sheaves of both clutches, I can leave it there for about four seconds. Is that too hot?
The main jets are PTO 152.5 and 150 for both center and mag. I ride around 6-8000 ft and latelty it has been between 20-36*F. I was considering leaning the mains one step. I haven't gotten to reading the piston wash just yet but the plugs have been chocolate brown with a reddish tint.
The clutch temps are higher than I would like. After a long pull on a big hill when I put my hand on the sheaves of both clutches, I can leave it there for about four seconds. Is that too hot?
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bajardine
New member
I read over MrViper's post today in the tech section on piston wash and reading spark plugs. I think my plugs were very similar to the ones he listed as "trail friendly plug". I find it hard to believe that this could be the culprit for why I'm not making the power I think I should be. According to his post this has a margin of safety in there for a temperature drop at night. If that's so, according to SLP's jetting guide for my triples, that would be about one main jet size difference. I can't see one jet size making my sled run like a dog compared to my bro's MM 700.
Next time I'm out I'll play with the wrap on the secondary to see if I can bring down the clutch temps a little bit.
Any other ideas on the loss of power?
Next time I'm out I'll play with the wrap on the secondary to see if I can bring down the clutch temps a little bit.
Any other ideas on the loss of power?
I asked because lets say for instance if the cdi box was not advancing the timing , the engine would show a rich mixture and loss of power. if you have compared it to the post made before and it looks good then its not the jetting, or likely the cdi box. I ask certain questions because theres a process you have to use to pinpoint a driveability problem.
So you have eliminated the head set up, now the jetting is good, powervalaves are set correctly and the servo motor is operating correctly,the rest of engine must be in decent shape to have 96% on a leakdown. This would leave a driveline parasetic loss, is the track way too tight? have you ever looked at the driveline bearings? what about the tension on the drivechain?
I am sorry to ask questions but theres not much left enginewise to be wrong, so I would have to look at the turning of the track.
So you have eliminated the head set up, now the jetting is good, powervalaves are set correctly and the servo motor is operating correctly,the rest of engine must be in decent shape to have 96% on a leakdown. This would leave a driveline parasetic loss, is the track way too tight? have you ever looked at the driveline bearings? what about the tension on the drivechain?
I am sorry to ask questions but theres not much left enginewise to be wrong, so I would have to look at the turning of the track.
bajardine
New member
I've been doing a little reading on here and I'm beginning to think that I may be running my track too loose causing it to balloon and rub on the tunnel. I was told I could run it looser than stock specs when I put in the anti-ratchet drivers. I may have gone too far. I will tighten it up and see what that does for me. I was just into the chaincase last week and the chain tensioner is just finger tight. The left drive axle bearing was replaced about 5-700 miles ago.
Now considering the parasitic drag, I can see how that would lower my track speed and hinder my performance on the hills. I don't see however how that would cause me to have to run weights much lighter than I should be.
As far as reading piston wash, I've read MrViper's post on it but is there any other sites someone might recommend that would have more pictures of stages between rich and lean? I bought a light wand light that I can stick down into the plug hole but I still have a hard time seeing the wash very well, especially on a sunny day. Does anyone make a scope for reading piston wash? I would imagine maybe something like a doctor uses to check eardrums??
Now considering the parasitic drag, I can see how that would lower my track speed and hinder my performance on the hills. I don't see however how that would cause me to have to run weights much lighter than I should be.
As far as reading piston wash, I've read MrViper's post on it but is there any other sites someone might recommend that would have more pictures of stages between rich and lean? I bought a light wand light that I can stick down into the plug hole but I still have a hard time seeing the wash very well, especially on a sunny day. Does anyone make a scope for reading piston wash? I would imagine maybe something like a doctor uses to check eardrums??
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