Engine mountings and location on the new build

[alexanderfoti]

Hi all

I am currently test fitting the engine in the frame of the XJ. Here are some pictures:





Now if you look at it from the right hand side, you can see there may be fitment issues with the engine and flywheel. I could modify the frame but then are there any extra things I need to do with the paperwork etc?

Any thoughts?

[tappy]

I'd use a smaller diameter flywheel. If you give it a decent amount of mass at the rim then you can still get plenty of momentum without the diameter or a huge increase in weight. Given that it's a round thing it's easy to machine and much less imprecise than hacking the XJ frame about.

At the top I'd check and see how much taller the rocker cover is than it needs to be - looks like about 12mm on my Hatz engine so I'll be cutting them down.

You could also angle the engine forward so with the rocker in the "roof" of the frame, the crank (and flywheel) would be further back. There should be specs available for the maximum permanent and maximum intermittent lean angle of the engine. Also depends on how much space you've got for the gearbox.

[pietenpol2002]

If you could in fact make it fit by turning down the flywheel as Tappy suggests, the loss in rotating mass will be compensated in part by the mass gained in the pulleys you'll be using - even after removing much of the center from the larger. Pull out the scale and do some comparisons. Consider also the quote last week from Boxotto - "the other mod i did was lighten the flywheel 9 lbs. that mod works great and my idle only increased 100 rpm and was still easy to start. original fly wheel was 24 lbs".

[gilburton]

Will the starter fit in there?? If so I would modify the r/h down tube to clear the flywheel i.e. bulge it out by either making up a small loop and welding it in or cut the r/h tube above the top original engine mounting and bend it out(with heat)then weld in a small joining tube.Get someone else to weld it if you don't feel competent.If you need to do both tubes you could weld on the new tubes before cutting the old ones to avoid distortion??
After that it's just a flat plate for an engine mount and you're well on the way!!
It won't affect your MOT if done well.
Make sure you leave the plate on the tube with the numbers! So don't mess with that.

[alexanderfoti]

A couple of options here.

I do intend to angle the engine forwards, as that rocker cover looks like its made to fit in that little cradle at the top of the frame!

I think I need to find out exactly how much space I need behind the engine for the gearbox. I do like the idea of adding slightly elongated tubing at the front to clear the flywheel (as using a smaller flywheel would still mean that the starter wouldnt fit as gilburton mentions). making the flywheel smaller would also work, but I would need to re-figure out how to attach the starter, as if I make the diameter smaller, it will no longer fit

Annoyingly that Vin plate is right where I would need to weld the tubing! So I may need to re-locate that.

I am confortable doing the welding myself, I will test it to make sure the weld is strong before I consider riding it!

I think, if it clears the wheel then it should be fine.

Here are some mockups:

[alexanderfoti]

Thanks all

[coachgeo]

IMHO build a whole new basket/subframe for the engine to sit in. Do you have access to a tube bender?

[alexanderfoti]

IMHO build a whole new basket/subframe for the engine to sit in. Do you have access to a tube bender?

I would, that would be the best option, but I dont have access to a tube bender (or the funds to buy one at the moment )

[coachgeo]

Some have had success with Pipe benders to bend tube filled with sand, salt etc.

you could also check with local 4x4 clubs, local race tracks etc. to build a list of names to contact. Think you would be surprised how many folk out there have tube benders. Lots of kits out there for build your own too. Some Harbor freight like tube benders, beefed up may work fine for the size of tubing of motorcycle frames.

[alexanderfoti]

Hmm a possibilty for a pipe bender then. I have just been out to measure the tube and at its largest its 1 1/4 inches wide. So a 10 ton hydralic pipe bender would do ( they go for around 80 quid on ebay)

I could ask around locally, maybe a mechanic mate of mine has one....

[gilburton]

Maybe you can hire one??

[alexanderfoti]

Good idea actually. I will check that out too.

have a look here:

https://www.dieselbikeforum.com/view ... =31&t=2509

I have test fitted the gearbox and looked at a couple of different mounting scenarios. I think the change is small enough to maybe go with the modification method rather than a whole new subframe. Im not sure yet.

[gearhead1951]

do a google search for diy tubing bender , you would be suprised at what will work !!