750 big bore oil leak?

natemeins · Posted: March 24, 2008, 7:31 pm Post subject: 750 big bore oil leak?

Hey Fellas,
Well, I've got Mike's 750 big bore mod installed, and man what a difference! Only one problem: the new cylinder block does not use the old cam chain tensioner boss. You thread the pushrod assembly directly into the cylinder, and since you don't use the boss there is no dust cap to keep oil from getting everywhere. So that's my question: you guys running this mod, are you having the same issues? If so is it something like it'll only drip a little and quit or will it keep dripping? If it does continue to drip what are you guys doing to "catch" the oil? Just curious cause even though i've only ridden it maybe 15 miles so far it really made a mess. Any suggestions would be great!

natemeins · Posted: March 25, 2008, 5:37 pm Post subject: Re: 750 big bore oil leak?

Maybe I should mention I have a 75 engine that has the type of tensioner that the dust cover screws into the boss. Doing a little research it looks like the 76-79 models have a type that the dust cover screws to the pushrod assembly itself. Seems like something like that might fix my issues. Anyone have an extra they're willing to pass along?

Cooltouch · Posted: March 25, 2008, 6:09 pm Post subject: Re: 750 big bore oil leak?

Got any pics of this? Have you contacted Mike yet to see what he has to say?

I'm kind of curious about this. It seems very odd that there would be no cover for the cam chain adjustment mechanism.

Best,

Michael

xs1961 · Posted: March 25, 2008, 7:08 pm Post subject: Re: 750 big bore oil leak?

Yeah,can you show pics ? I'm about to buy one of these kits from Mikes Dutch distributor, not sure what youre explaining ..

natemeins · Posted: March 25, 2008, 7:08 pm Post subject: Re: 750 big bore oil leak?

Yeah, I thought it odd too when I got the new cylinder block and saw it was just one big threaded hole. And in my case, it may not have been such a cool idea. I guess this way he can sell it to any engine, no matter the style of tensioner. I plan to drop an email to him and see what he thinks. I still think an end cap from a 76-79 will work, just need to find one.

natemeins · Posted: March 25, 2008, 7:15 pm Post subject: Re: 750 big bore oil leak?

Here's a few pics

xsjohn · Posted: March 25, 2008, 7:36 pm Post subject: Re: 750 big bore oil leak?

THe acorn nut and the tightening nut for the later models should solve that problem .....clinch them together and leave the nut there that secures the adjustor bolt....sorry for the lousy ebay pic........

200135091506

xsjohn

natemeins · Posted: March 25, 2008, 7:55 pm Post subject: Re: 750 big bore oil leak?

Thanks, xsjohn. Headed over there now and buying it!

xs1961 · Posted: March 26, 2008, 9:34 am Post subject: Re: 750 big bore oil leak?

Natemeins,any chance you could show us a picture of the barrels & head from the side & front? I'd love to see the difference the extra finning makes ... Thanks
Im a gnats nadger away from ordering one this week !

natemeins · Posted: March 26, 2008, 1:34 pm Post subject: Re: 750 big bore oil leak?

yeah I'll get a few posted later today. It actually looks good, like it was a stock unit! But the difference in low end power from stock was completely worth the price. I'm even thinking of dropping a tooth or two on the driven sprocket. FWIW, I also added mikes performance cam and iridium plugs, as well as a very mild porting of the head.

Mikesxs · Full Member Joined: Feb 06, 2007 Posts: 134 Location: FL

Cylinder uses whatever adjuster and cap assemply (and the seals) that came with your 74-84 engine. It will leak if you leave the cap off and do not use the seals (and so will the stock setup leak if you do the same with it). All of these performance parts have been tested. Don't forget to break in these parts and change the Oil !
Mike Lalonde Mikes XS

natemeins · Posted: March 26, 2008, 9:16 pm Post subject: Re: 750 big bore oil leak?

I hate to disagree with you Mike, you would know better than anyone, but in the case of at least the 650B models (1975) the dust cap screws into the 6 bolt tensioner plate, not the end of the adjuster bolt. And since there is no way to bolt the stock mount to the new cylinders, I cannot use the stock dust cap. xsjohn seems to have grasped a solution and use the dust cap (acorn nut)from a later model. Here's a pic of what my tensioner assembly looks like.

natemeins · Posted: March 26, 2008, 9:23 pm Post subject: Re: 750 big bore oil leak?

Here are those pics, xs1961 that I promised you. I think they look awesome, and the performance is great!

natemeins · Posted: March 26, 2008, 9:24 pm Post subject: Re: 750 big bore oil leak?

Here are those pics, xs1961 that I promised you. I think they look awesome, and the performance is great!

xsjohn · Posted: March 26, 2008, 10:04 pm Post subject: Re: 750 big bore oil leak?

Im jealous....now it looks like it just didn't come out of a concentration camp like the stockers do.......and about the acorn nut......my mother said I was useless as tits on a bull.....na na she was wrong......at least once....

even on the newer ones the o ring can leak....mine die....got the oring out of the acorn nut and faced the surface a bit on a belt sander so the o-ring stuck out a few thousands more and no leak.......

xsjohn

xs1961 · Posted: March 27, 2008, 3:27 am Post subject: Re: 750 big bore oil leak?

Thanks natemeins,looks great,much like the Morgo 750 kits I used to fit on Triumphs , the finning on those was larger & blended in with the head just like this.
Im fed-up pissing around with my 840 so Im selling my last one and ordering my 750 kit today from Mikes Dutch distributor, cant wait !

xs1961 · Posted: March 28, 2008, 5:29 am Post subject: Re: 750 big bore oil leak?

Oh dear..He wants 500 EUROs = £390 = $700... Shocked

I'd better start selling some spare 650 stuff.... Crying or Very sad

What Happened to 650rider.com?

Yamaha xs650