Airhead

Yeah thats what I meant, now it looks like its worth investigating other things first although we cant discount the seals on such an old bike! Having read what you just posted, Perhaps there is and issue with carburation or fuel supply Take off the fuel line from the carb and open the petcock, you should have a good strong flow of fuel...have you? Have you stripped and examined the carburettor?

Inside the front brake plate you will see the speedo drive gear has two 'arms' on it, they stick out from the centre in opposite directions 180 degrees. These arms are often bent backwards because the people who assemble the brake plate dont see that the two arms must be aligned with the slots in the wheel hub when the brake plate is re fitted, check it out...bend them back...and re-assemble carefully if any of this applies While you have the brake plate off make sure the helical cable drive gear is turning as you rotate said structure with 'arms'

Before you dive in any further lets look for evidence that may go someway to proving the crank seals have gone bad. You say you have an issue with the engine revs climbing dramatically even with the throttle closed? This behaviour would suggest the left hand seal is passing air to the crankcase...so theres a simple test to confirm this start the engine and with the straw attached to the aerosol spray some WD40 through the slots in the flywheel, take aim at where the crank seal will be in the centre. It this seal is faulty you will see the engine revs drop back down, you will certainly see or hear a change in the engine behaviour, give it a try

yeah good puma, maybe just go for little rides at dusk rather than darkness until you have confidence

Flyday has a CS5 perhaps he can give you some measurements for those...legs and spindle

30th Sept 2012, Ramsbottom (Not Upper Ramsbottom ) Cricket Club http://www.northmanchesterbikeshow.co.uk/

good to see you and the old girl 'getting it on' again Jason bet she's not best pleased about your new floozy eh?

in mi best cocney accent...wot wi Xmas camin ap an awl

I think it can be done with the engine in the frame mate but the drive pinion and clutch would have to be removed has the gearbox got a breather pipe in the top on that model? Can you smell petrol if you remove the gearbox dipstick? With extended use does the gearbox oil level change?

No thick oil never did them any harm I oil mine with 220 viscosity gear oil is the main jet the standard size for the bike? Perhaps the choke isnt seating, is that a possibility? RH crank seal passing and burning gearbox oil...is that also a possibility?

Yes you should replace those old old crank seals

The predecessor to this model had a 240 jet as standard, mine ran sweet with a 250 on there but I'll admit it may be a jump too far...Judging by the degree of damage though it's likely to need a fair bit bigger than 210 The Hexagonal jets are in increments of 5 from size 50 to 195 and in increments of 10 from 200 to 500

From what I've seen in the past it's a difficult subject to restore! Never seen a parts book for one but we'll help where we can Some of the older yams had the key number stamped into the lock...check it out

Greetings Matt, you'll fit in well here your bike is similar to one we had here in Europe (DT175MX) we have a couple of your countrymen here also who have the same bike

the key is...to find the one thats too big and causes the engine to cough and splutter when the throttle is fully opened, then start downsizing until it runs sweet. It's a bit guesswork at first but jets are cheap even genuine mikuni ones, id be surprised if you needed any bigger than 250 but buy a few sizes...they go in increments of 10

if 'jiggling' the key makes your tail light flicker then thats a good place to start eh?

We will await the other thread, and perhaps a quick intro as you're new

you're ok Matt go to sleep

yeah the carb is difficult to get in and out I remember that, however it is always done with the airbox insitu, I dont even think you can get the airbox out without removing the rear damper! It's not necessary anyway so leave it in. You may find that if you fit the carb inlet into the airbox duct first...then force it all rearwards the duct will 'give' and you can swing the front of the carb into place into the reed assy....Thats how its done IIRC If all else fails with the bowl screws you may have to get a grip of them in the sides of some mole grip jaws to undo them. I would replace them with stainless cap screws, buy those along with your new jet(s)

Probably a good job you stayed with the slowcoaches on the squires meet eh Jason

Greetings and

Changing the jet is easy, just take off the float bowl from underneath the carb, you will see the jet there...a brass hexagonal thing with a hole in it and a number on it, i would say only buy genuine mikuni jets. just see what size is fitted and buy a couple larger ones....like I said earlier i'm thinking 250 will be about right depending on whats already in there. Allens sell them cheap .........google allens mikuni Take care undoing the float bowl screws, they are easily chewed if your driver is not a good fit!

I always use Yamaha or a good Japanese equivalent, these are more likely Chinese/Taiwan copies but thats why they're so cheap Having said that..Because it's so hard to come by the good ones I wouldnt have any hesitation myself It doesnt mean that it was the cause of the heat seize though...up the jet as well if it will run right

Aye thats the one Richard, either 2A7 or 2N5 (Both the same)

Watch out for the salt bippo, maybe treat your bike to some ACF50...I understant its very good at it's job and without it the salt will EAT your pride n joy!