The rule of thumb is to both loctite , then torque the central screw up mate, as to the cover use a penny washer and m5 or m6 (forget right now) hex bolt, should hold it in place till you can replace it.
Luckily the pins dropped into the exhaust not the cylinder which is a result. Had to get a new one in the end, as the thread that holds them together had been stripped. After sifting through about 20 different yamaha engines at the breakers finally managed to find one lol. Also found another 3mb p cylinder with head while I was there might go back down there sometime and take it off the engine, got to be worth it.
Might? I'll stand in Burtons window stark bollock naked for a week, if your not down there looking for those 3MB bits marked with a 'P' before next weekend.
Haha who's burton, im sure he wont be impressed. Looking at my current bike funds and amount of parts i've aqquired in recent months It will probably be a while! There must be others that have this un healthy obsession with spare parts!
For the more refined of us, Burtons tailors are for the more concerted Gentlemans outfitters. innit
-- Edited by NEV on Friday 28th of September 2012 04:57:10 PM
Yeah I don't really do tailors. I wreck clothes alot so buy t shirts for 3 quid tracksuit bottoms. comfortable and cheap. If i'm seen wearing a suit someones probably died...
Yeah they're really cheap actually. I might grab that cylinder on monday see if I can blag it for £40 lol. Thing is I know for a fact no one will be able to find it, they probably don't even know its there lol. Only thing is it means I have to go and disassemble an engine to get it lol.
You sure, I thought the P one's were the same as dt one's but were just ported a bit? But yeah I had a look at the piston while the power valve was out, bit of blow by so due a rebuild anyway, might as well stick something a bit quicker on it :D
Only barrels Nicosil plated are the 4FU and 4FL barrels, and only the TDR and TZR went with these in the 125 bikes anyroad. They were ported differently as Andy says, but not aggressivly ported for performance and speed as the 4DL's were, but more for endurance and longevity, have read that the Nicosil plated 4FL & 4FU's were slightly down in power compared to the 3SH, 4DL stuff, but better than the 3MB stuff
-- Edited by NEV on Sunday 30th of September 2012 08:22:17 AM
4fu's were down on power compared to the 3mb barrels....BUT,and it a big but,they ran flat top pistons bang in a domed top one and compression goes through the roof
my favourite bit about the 4fu's was the tuning potential (more meat on the castings of the transfers)
3mb
4fu
better coice for reshaping the transfers. have seen one with the transfer bridge removed,dont know what it ran like though (probably 5hite...)
4DL's get about 12:1 compression ratio,IIRC, so maybe they had the domed one in that, I do remember the chap at Cornish motorcycles saying that mine was a higher compression TZR piston, and am sure that was domed too.
Aye deffo, problem I have is, do I look out for a genuine 4dl barrel and head, the one with the 'O' ring cut out on the barrel top, and if so how do I go about putting a larger piston into it, as in when they do the re-bore on a 4DL barrel, do they also re-cut out a new 'o' ring groove, or keep with a 3MB one have that bored out/re linered for a 5mm oversize piston, and let one of you dremmelheads have their wicked way with it to get it somewhere near, in the porting side of stuff.
the o ring one will be a pain in the butt to find,but will give massive power as standard. think thats the best bet. there has to be a small stockpile of NOS barrels/engines somewhere out there? do remember yamaha found a warehouse full of yz 490 engines that they "forgot" they had (hence the wr 500)
There's a 4FU one there as well but didn't bother with it because I thought they were down on power. Although the exhaust port does look bigger on it, might have to give that one a go as well sometime lol.
Check the bore on it PH, because if its well skrawked its about £130 to have it nicosil plated, but if you do go for it and its skrawked ta buggery, well ya might as well get hung for a sheep as a lamb, and go to town on it by re-boring it, getting a larger piston and then re-plating it.
So the 3MB P is not nikasil plated? Thats interesting. I'll suggest he gets his barrel re bored and a new piston then. I thought all the 33bhp models were nikasil plated which was how they got the extra bhp through smaller clearances. Thats good news.
I'm still gutted he lost the sp barrel, or at least I'm fairly certain it was as it had boost ports. Said I'd come and get it later in the week, only wanted £25 for it!
bang in a domed top one and compression goes through the roof 
