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Discussion Starter · #1 ·
Hey guys finishing up a rebuild on a 04 300 mxc and ran into a couple hicups/issues.

1st issue is the stopped plate that adjusts the power vavle timing is broken on the end. Any way around it or am i stuck until the new piece comes in.


2nd question is checking x dimension (piston to head clearance) when turning flywheel to tdc theres a spot where i can hold flywheel for the pistons highest poing but if i let it go it will drop A bit.

So when measuring the tdc spec do i measure from the pistons highest point in the cylinder or "the resting" tdc

One example was that i had a too thin base gasket and piston would hit the straight edge turning motor over. But would not hit if at the "resting tdc position"
 

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TDC is uppermost travel of piston. Measurements are taken there.
Not familiar with your description of PV adjuster gizmo. Can you send picture or description?
 

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Discussion Starter · #3 ·
TDC is uppermost travel of piston. Measurements are taken there.
Not familiar with your description of PV adjuster gizmo. Can you send picture or description?
thanks also for when measuring the dimension X just to confirm im measuring the edge of the piston closest to the cylinder wall.

I have the thickest base gasket in there now which I believe is the .04 and I believe the dimension X is at 0 though i do feel it faintly making contact with the straight edge. so i may add the .01 gasket to give it the .01 "x dimension gap to be safe.

Here's a picture of the power valve flap that broke
 

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It is common practice to resurface cylinder base for modifications. Some for trueing gasket surface, others for changing port timing, squish or both. Use gaskets as needed to restore correct dimension. Best to use thick gaskets if possible to establish correct dimension. One thick gasket is better than several thinner ones if possible. Your PV arm appears to have broken stop tab. Quick touch of a TIG welder or brazing torch will fix that easily until parts come in. Weld or braze a small flat washer on there and heat it and bend it to prevent overtravel of arm.
 

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Discussion Starter · #5 ·
Thanks the cylinder is oem as far as i know. Im doing the x dimesnion measuring from the edge of cylinder wall as the piston is slightly domed. So hopefully thats right

For the stop tab good idea on just welding a washer or something. Im kind of curious though wouldnt the "actuator" rod control all that? And the stopper just being an "additional" precaution?

I figured i would of had to re adjust the power valve but the actuator puts it spot on. Though im also missing that little locking pin (issues when buying a bike that was taken apart by previous owner)
 

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If I understand function correctly the tab is used to ensure PV closes. It uses a spring to request it closes but if it refuses to close the tab insist on it. My understanding was dimension was checked at side of cylinder. You can find video explanation on slavens racing website for clarification. Some of his videos are very helpful because information is visual
 
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Discussion Starter · #7 ·
thanks ill check his vids out! if i just measure the very edge then the one gasket at .04" is good to go!

couple pics i took as i went... once I get the motor running and all checks out ill be throwing on all new plastics as well.

did some chassis maint too new rear wheel bushings / bearings, throttle cable etc. motor is all together for the most part aside from dealing with the valve stopper and the actuator clip. so it wont see the head until i can get that set up (to ensure valve is set to spec) but ill be putting motor in chassis shortly




 

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Looks great! Well done. Keep posting pictures as you progress along. Lots of love here for the restoration projects.
 

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Discussion Starter · #9 ·
Looks great! Well done. Keep posting pictures as you progress along. Lots of love here for the restoration projects.
Hey quick question! i forgot to order the OEM copper crush washers for the head. I manage to find some copper washers here that are the exact same size however double the thickness.... whats your take on that? run em?

reason im asking is because i got a trip coming up and the oem crush washers wont be in on time if i wait.
 

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No worries. You can reuse the old ones in a pinch. Slightly thicker shouldn't hurt either. If your cylinder head o rings are sealing properly the crush washers are mostly for keeping crud out of threads.
 

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Discussion Starter · #11 · (Edited)
Thanks! I ended up using the thicker ones i had on hand. the oem ones were pretty rough

Got motor all done (ish) for the most part. I ended up getting the stopping tab welded. All im missing now is the little locking pin for the PV actuator rod.

got motor fired up and did a quick 5 min ride around the yard and so far its been good Only issues is petcock o ring is leaking, brakes need to be bleed as they barely worked and the forks seem to be leaking a bit. thinking maybe its just some dirt so may try and just clean the seals.

Burning off some of all that assembly oil / grease. it was smokey the 1st min.. guess I went a little excessive during assembly.. but it cleared itself after a little bit.

 

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Very good. Not to worry about assembly lube smoke. Makes it harder for your competition to see you :D good luck with your build. continue to post your progress. Be sure to post plenty of pictures.
 

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Discussion Starter · #13 ·
haha yeah.... it cleared out any bugs in the backyard for a good bit thats for sure. ive done a few rebuilds but 1st KTM motor some motors are extremely picky vs others this one seem to clear out pretty quick. will def get some more pics up of it riding! im hoping well be able to bring it to our camping trip this upcoming weekend but need to get the brakes and forks dealt with.


On that note.... have you ever had any much luck cleaning out the seals when they leak. what oil weight and I can imagine how much oil would all depend on how much leaked and without a tool to check it im SOL?
 

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Not to worry much about fork seals. A thin slice of flexible plastic can be carefully inserted between fork seal and fork leg and carefully rotated around while spraying WD40 or CRC into opening created by plastic tool. If your leak is caused by debris or grit on seal the penetrating oil can help flush it out and prolong your seal replacement. If the fork bushings are worn the leak will persist until forks are rebuilt. Careful adding fork oil. Too much will hydro lock forks. They don't hold much oil. Unless you drain and refill them it's probably best to leave them. If they are empty you would know it as they will bounce like basketball.
 
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Perfect choice. Give it rounded hook shape and she's golden. Have a look at the commercially available fork seal cleaners and use as a pattern for your design. They are called seal savers. You can probably google them for a picture. The home brewed versions work just as well. Make sure your design has no sharp edges to cut seal and you're golden (y)
 

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Discussion Starter · #17 ·
got the forks cleaned out and as you mentioned I just cut out a pop bottle copying one of the seal savers I good bit of dirt came out of the seals and wiper seals didnt add any oil or anything. I didn't have any fork seal cleaner so I ended up using electric contact cleaner which seemed to push dirt out non the less and safer on seals then other products i had on hand.

I will say the brakes are being a little bit of a head ache. should these brembo brakes not go rock hard at full lock? previously the front brakes would barely slow the bike and the back brakes were non existent (you could turn the rear tire by hand with the pedal pushed all the way down)

I bled both the front and back, the front SEEM to work better and we can now lock up the rear (when spinning the tires on a stand). but i haven't tested in dirt yet as we are trying to fix the petcock o-ring. (their sold out here) unless i order one from KTM though it will be too late for this weekend's camping trip we plan on taking it to
 

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If you have a sample of the o ring you can present it to an industrial hardware store for replacement. Best to use viton if possible but buna will work if needed. Some auto stores sell o rings also. Your brake fluid may have become contaminated during storage. Bleeding and adding fresh brake fluid may help. If trouble persists after a few weeks storage it usually indicates master cylinder is allowing air back into system. Reverse bleeding will fix it temporarily until you are ready to repair or replace master cylinder
 

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Discussion Starter · #19 ·
yeah im supposed to call a guy a little later today to try and match it over the phone for him to make one. time will tell. if all else fails i was going to use some black RTV on the old o ring until i can get a new oem one in.
 

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Spliced o rings or silicone are both a no go for any fuel service. Very bad idea. Spliced o rings are cemented together with glue. The glue can be degraded or dissolved by fuel or fuel additives. Silicone RTV is also degraded in fuel or fuel additives. Even the stuff that claims it is safe for fuel usage can be degraded by additives in fuel.
 
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