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Problem With Fresh Topend


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I dont know, its something to think about. If you can get away with a hone and its just that one cylinder that is scored it'll probably only cost you a couple bucks for the hone to have a machinist do it, a couple bucks for the rings, and 16 or so for the orings (which I would replace anyway for the fact to eliminate something that could be causing a problem). If the piston has scoring on it i'd replace that too which would be 60 or so dollars.

 

If you just hone you dont need to replace the pistons, just rings. You need to do that so they seat together with each other. If that one piston is scored though I'd replace it, you dont want to be 100 hours in and break a skirt because it was scored.

 

I'd wait for passion or someone else to reply on these thoughts as well. I'm no engine builder, just been around here and been working on stuff for a long time and have seen a lot and these are my thoughts of what could be causing the problem. My main thought would be what caused the scoring on the cylinder wall?

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Justin, that burn pattern on the domes is absolutely perfect. Notice on the Left hand dome how one side(exhaust side) has a little discoloration and the back(carb side) and partial sides are really clean, they look like that because of how I set up your transfer ports. The mixture is aimed at the rear and up more than normal coming out of the transfers and washing those domes clean at the rear and sides. That is picture perfect burn pattern...just what I had in mind. A coolant leak will wash those pistons clean and obviously thats not happening. Its possible that if you would have rapped it out bigtime before that last compression check like SDD suggested, that the right dome would have been clean as well. Take care of yourself and get well...I dont see anything that scares me in the least goin' on with your engine. Im sure you'll get to the bottom of your carbon issue once you get back on your feet...Jim

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Justin, that burn pattern on the domes is absolutely perfect. Notice on the Left hand dome how one side(exhaust side) has a little discoloration and the back(carb side)  and partial sides are really clean, they look like that because of how I set up your transfer ports. The mixture is aimed at the rear and up more than normal coming out of the transfers and washing those domes clean at the rear and sides. That is picture perfect burn pattern...just what I had in mind.  A coolant leak will wash those pistons clean and obviously thats not happening. Its possible that if you would have rapped it out bigtime before that last compression check like SDD suggested, that the right dome would have been clean as well. Take care of yourself and get well...I dont see anything that scares me in the least goin' on with your engine. Im sure you'll get to the bottom of your carbon issue once you get back on your feet...Jim

so it sounds like it must be leaking case oil then into the crank? I checked the oil level and it was still full?

 

What do you suggest I do next to find out what the issue is? Should I pull the cylinders off? Do I need to hone my cylinders and replace the pistons and rings?

 

Or should I open up the carbs and look in all the jets first?

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Leave the jugs on, your compression is reading better than it did after 2 hours of use, obviously the rings are seating in just great. Wipe off the pistons with some carb spray and reinstall the head. Eventually after you figure out that cold pipe at idle everything will be just peachy. How does it run?...Jim

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Are you sure your main jets are correct? Have a pic of your plugs after a wide open run? what is your filter setup, lid, no lid? You are running 370 mains right? 360s on mine was rich...

 

I wouldnt worry about needing new pistons/hone/etc., mine has light scuffing as well but its not gonna turn into anything.

 

If it was me, I would put her together, take those stupid TORS caps off, get a tor elminator kit, or better yet get rid of the stock carbs, sync the hell out of them first at idle then for movement. then check your jetting especially the mains.

 

Then watch you dont detonate by raising the compression and running pump gas if you are.

 

later

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Are you sure your main jets are correct?  Have a pic of your plugs after a wide open run?  what is your filter setup, lid, no lid?  You are running 370 mains right?  360s on mine was rich...

 

I wouldnt worry about needing new pistons/hone/etc., mine has light scuffing as well but its not gonna turn into anything.

 

If it was me, I would put her together,  take those stupid TORS caps off, get a tor elminator kit, or better yet get rid of the stock carbs, sync the hell out of them first at idle then for movement.  then check your jetting especially the mains.

 

Then watch you dont detonate by raising the compression and running pump gas if you are.

 

later

yea I went with 350's and did a WOT test and they were to lean.

 

THey gave me a 260 and a 360 on mistake so I went right to the 370's and they worked alot better. Might be slightly on the rich side, but much better than the 350's.

 

Im running 50/50 mix with 110, or recently 114. I have been trying to sync the stock carbs but they suck. I can't wait to get some 33's or 30's.

 

I was just thinking about pulling the cylinders mostly to make sure the rings are alright on the piston. But if I shoudl jsut leave them on I may do that.

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Hi guy's. The right cylinder(when sitting on the bike) is the clutch side, so if that crank seal is leaking, it can suck oil into the crankcase. Is it your right cylinder or your left? Also it is not likely that it"s burning enough oil to be very low on your dipstick. You can get it preasure tested, or just put it together and check your carbs first. Goodluck!

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