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XJ750 Exhaust question and advice needed pleeeeease!


davie6711
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Airhead,

Was only teasing mate.

You see the last photo? The 2nd port from the right. I think i'm going to have the hole for the bolt re threaded unless I can manage it myself next time i'm off.

What exhaust issues you having then?

Davie

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dont rush into re tapping the cyl head Davie! unless you are certain theres a problem with it

so this port has two threads, how is it with each of them...and for that matter what about the 4th port...just how many of these 4 in total internal threads does the stud/bolt screw into?

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Hi Airhead,

As luck would have it the rest of them are ok and it's only one of them on the 2nd from right.

Looking back on this thread you'll see what came in the box from motad and what I managed to reclaim from the old system. The ones from the box are far too big and don't allow any room to see the threads. The seals I reclaimed for the old system looked to be perfect but on the third and 4th down pipe the collar/seal is to small to fit up the downpipe to the end so after trying to fit them it looks like i'm going to have to cut them a little bit to make them fit the down pipe. Sorry for the ramble but it was 4.30am when I started to write this. As usual all advice very gratefully received.

Davie.

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Hi All,

First a quick recap of what's happened so far..........as you can see i'm trying to fit a new 4-1 motad to my bike and have asked many questions and have received great advice in return.

I mentioned before that I may have to drill out a broken stud, the top left on number 3 cylinder. I've been racking what's left of my pickled brain to remember how that particular stud came out and it's just come back to me!

I'm going to put up a picture in a mo as I would like a vote whether to repeat the bodge that was there in the first place or try and do it right.

IMG_1596_zpsdbf8f7f0.jpg

You can see something in the place where the stud should go...

b1190f2e-3deb-48af-ad46-5b2b731526e0_zps

If this photo has come out ok you'll see what I mean. The arrown on the left points to a threaded lug where the horn would fit. When I removed the exhaust there was a very long piece of threaded rod which went through this lug holding the horn on and then went all the way through the exhaust collar and into the head a little way with 10 mm nuts along the way. It went in at an odd angle.

Vote: Do I repeat the bodged job or do it right? Over to you guys.

Davie.

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Do it right Davie, no point in making the same mistake as the other numb nuts did, if you have a set of taps and dies then it should be easy to just straighten out the thread, although looking close it MIGHT have a helicoil in it which will be a bit harder than the normal head material so just take your time and see whats best. Good luck mate. :jossun:

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Hey Slice,

Thanks for that but `i don't have a set of helicoils and if you look or try to imagne where it is the frame is a twin tubular frame and it's awkward as fuck to get at.

Meant to add that the distance between the lug for the horn and the thread is about 6 inches.

A Worried Davie.

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Having more or less the same bike as you I know where your at, i was not suggesting that you fit a heicoil but that it looked like there was one in the hole? Might be wrong of course but if there is one in there it might be possible to recut the thread in it to accept another stud, that seems the only way your going to get around this without taking the head off. That isn't a hard thing to do but best not done if you want just a quick fix, if you want to remove the head then it should take about an hour to get the ancillaries off and another hour to get the head off then you can take it to your local engineering work to get them to cut you an nice new hole. Look at my vehicles and you will see what's involved as I have just done this to the Maxim (same engine) cost about £90 including a nice new head gasket and a set of new head nuts, plus you can change the timing chain if you want to at the same time. Hope some of this makes sense mate, good luck. :jossun:

Just as an aside the tap to recut your thread should fit easily in the gap between the frame and the head.

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Hi Airhead,

To be honest I canny tell. It looks like it might be a lump of araldite or something like that. If you look at the first pic posted this morning you can see a yellowish blob of summit. I've tried to even thread a bolt in a little way but it just won't start at all. I'm tempted to repeat the bodge as I like both the the time and mechanical savvy to do much else.

It's quite a nice bike but won't be worth all that much I don't think but it does have an MOT til August.

What do you think I should do?

Spend so far: Cost of bike, £100 ish for the Motad system and £65 for a new rear tyre yet to be fitted.

Kind Regards,

Davie.

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Hi Airhead,

It looks poss the way to go much as it shames me. If I want to try an nut and bolt redo I have a YPVS LCII that would be much better tine spent me thinks.

Thanks as always,

Davie.

Any other comments/suggestions peeps?

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Hi Davie, I suppose if it works then put it back to how it was before, no need to get all het up about it, just seems a shame to have a nice new exhaust and then to do a Frankenstein on it, still really only you will know that it's not perfect and to be honest as long as the gases stay in the pipe and not up your trouser leg that might be enough. If it was me I would sort it out but if your strapped for time then it's a no brainer to just get it up and running after all the riding season is rapidly approching ie not pissing down or 4 foot of snow and ice. Just do what you have to and enjoy the bike. :jossun:

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Hey,

Airhead, you are right. I'll do it right. Decision made! The best advice yet is what you said. I will know it's not right and that will bug me.

Progress report when ready.

Davie

Whatever you do keep within your own limitations davie, make the best possible botch improvisation you can...whatever you do it need to be reliable and last well. If you make a balls of that cyl head trying to do it 'right' that will bug you even more...always beware of trying to drill out snapped off studs...it aint easy mate

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Airhead,

Thanks again mate.

Was talking to my mate last night and I think this is the way forward....the hole going in to the head is 8mm so I was going to try a 6mm drill bit and pray a wee bit and try to remove whatever is in there and hopefully reveal some of the original thread. Pipe dream maybe but you never know. If that's not successful then 8mm drill and get it retapped.

I'm messing about with three bikes at the moment and really need to prioritise. The Yam's nearly there apart from this exhaust problem, then I have a new rear tyre to fit and that will be my running bike.

I recently acquired a CBX750F. Had one years ago and have a soft spot for them but i'm get it painted pearl white at work and have a set of Castrol decals for it. Thoughts/comments?

I also have the GPz 750 with the carb issues. Would you believe that one new diaphragm is about £70!!!!???

Also have my 350 YPVS LC2 lying at the back of the lock up in bits, doing nothing and deteriorating slowly. It's well beyond my skill level so I have a wee back street bike shop fairly local and was thinking of taking it to him and getting him to start a rebuild on a kind of pay as you go basis ie when i have a bit of spare cash give it to him and get him to do the hard bits. Again thoughts/comments welcome as always.

Finally I have to say that this site is great, people are friendly and helpful. I was thinking of joining a Kawasaki forum for help with the GPz but got a fairly cold response so you guys are stuck with me!

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Hi Davie, Like the idea of CASTROL decals they always look cool, your GPz diaphrams at £70 seems a bit steep have you tried finding out what other bike used them? might be possible to rob some off of something else, if you can't fix your 350 yourself and can get someone to do it for you then that has to be the best way, as for your original problem take the head off and get it drilled and tapped, I won't say it can't be done but trying to retap a thread in situ is nie on impossible unless you have more luck than most of us plus you really do have to be able to see what your doing, good luck either way mate. :jossun:

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