Need help Inserting piston circlip

[Bruce CurtisMember]

.

By “wrist pin and bearing” do you mean the pin that holds the piston on the conrod and the sleave in the conrod?

Yep they’s the ones,
You don’t need a vice, in fact don’t put your rings in a vice, just hand held and nail file will do, no biggy.

BC

[TrentMember]

Oil rings were 0.8 and 0.5 and max is 1.0 so I’m installing the piton…. again! haha At least I’ll know its right though thanks very much – I would’ve hate to have learnt that after it was all back together or worse still when something went wrong!

Measuring the oil rings was difficult – I had to take them off the piston and slide the old piston into the barrel and then sit the ring on top and measure and it was difficult to get my feeler gauges into that corner. If I measured it on the piston is squeezed the ring out and gave a high gap reading.

[TrentMember]

Next question!

Is it necessary to give the valve faces and underside of the head a rub to clean it up? I’m guessing scotch brite pad would be too much so I’ll just give it a solid wipe with a rag.

[russell culleyMember]

hey austblue…the last piston i did was an XR and the compression rings were marked on the top face…one had a “T” and they wanted that ring in the top groove (wiseco piston)…..dont forget to stagger the two oil rings ……dont put gaps front or back as piston has more pressure there due to crank action…same with compression rings…how did you get the chain off? ….see you saturday fellah :woohoo: …..BTW my 2stroke piston has 2 rings and pegs in the ring groove to locate both rings..if front is 12 oçlck then gaps are at 4.30 and 7.30

[TrentMember]

Cam chain? It doesn’t come off it just slops down as you pull the cylinder and head off then you have to pass it up through the housing as you re-install.

1 compression ring and 3peice oil scraper – I put the gaps on either side and made sure they were lined up in the vicinity of the pins.

I’m done for the night now – had one of “those moments” that I have to share. I was torquing up stage 1 of the head bolts using my purdy new torque wrench and had the downsizer on to use my 1/4″ 10mm socket and I felt it ease up a fair bit away from the 40Nm I was aiming for. My nuts slipped up into my tummy like they did when my oil drain bolt eased up some time ago. I figured if it had done damage then I best test it and wound it on a little more and it let go completely! I took the wrench off and found that the adaptor had sheared off and almost fell over in relief.

Unfortunately that means that I can’t torque down the cam bridges but I’ll be able to finish that off tomorrow after I’ve bought a decent adaptor.

Speaking of the weekend, I’m still nervous about this water pump seal as my parts haven’t come in and I don’t want to rip the seal carrier off because I can’t see a way to do it without damaging it and I don’t know if they ordered a repair kit including the carrier and o rings or just new seals.

Fingers crossed!

[TrentMember]

I’m beat I sat up till 2am putting it all back together and replacing the water pump seal and it all seemed to go well but once I was done I couldn’t get it to kick over.

One thing I noticed which doesn’t seem right is that the cam chain seems like its not lining up during certain parts of the stroke. I marked the chain before I took it off and I’m confident I set the cam chain tensioner correctly but at a particular part of the stroke the chain lifts on the gears and is slightly slack between the gears. I checked my marks and the chain is still in the correct spot so I’m not positive this is the problem but I’m lost anyway.

To make matters worse I’ve stuffed my neck too I’ll be taking the bike to KTM this morning to see what they can do for me but I’m flat out at work so I don’t think I’ll be able to give it too much attention today.

[DeanMember]

Trent,not being a fourstroke whizz but is the Cam chain sitting correctly on the bottom drive sprocket? Best of luck with it mate.

ollie

[TrentMember]

The way it was behaving I think the chain must be stretched but I don’t think this would cause it not to start and the mech said the same. They were busy but hoped to get to look at it today and let me know what they think is wrong.

I’m going to need counselling soon, that’s the second week in a row I’ve missed a ride because of this problem! I priced a new 250 with the 280 kit while I was there yesterday but its far too much for me to justify at the moment.

[AlexMember]

The crank locking bolt would have kept the whole setup at top dead center. The cam marks would have faced each other (pretty much exactly). Mark a chain link and the cam gears so you can put all of it back exactly where you found it. Remember it all seems out of wack until the followers and tensioner is put in. There should be no mistake with this on a KTM.

Don’t forget that the piston rings have to be positioned according to best theory as the piston has no locating pins as you know. If the ring end gaps are in the wrong position you have more chance of blow by and increased wear.

[TrentMember]

Turns out it had a dodgy spark plug connection. I’ll have to chat with the mechanic more when I pick it up for more details. I did check and it was sparking but tbh I’m no expert at knowing if there’s a problem – it sparked so i thought it was ok.

I also need a new cam chain soon – are they difficult to fit?

[Author]

Posts