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TR7 Engine Orientation

830 views 7 replies 5 participants last post by  rambo 
#1 ·
Evening Folks

I'm lashing together a TR7 special based loosely on a 1981/2 Tiger Trail for reasons that seemed good at the time but escape me right now....

Anyway - I'm at the dry build stage and wheels and frame are mated up. As you will see it's a bit 'ahem' - non-standard-ish with knobbly tyres, a new swing arm and some USD forks on the front from a KTM Duke.



So, my question is: Should the TR7 (or T140 for that matter) engine sit parallel with the ground? If so where would that be measured?

At the moment an imaginary cylinder gasket is horizontal as measured with my trusty spirit level. OK the engine cases are empty and there's no weight on the bike at all, but is that where I need to be? I have seen all sorts of engine configs in the past with the engine tilted back as all angles, but so long as cool air gets to where it needs to go is that a problem? Are there any oiling issues with excessive engine tilt?

I'm just curious. I do have the capacity to shift the forks up through the yokes by about 3 cm if necessary. I may need to do this later on, but as they say - knowledge helps you understand why you **** up, but ignorance is bliss!

Any thoughts anyone??

Cheers

KitKat
 
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#6 · (Edited)
Hi KitKat, Looking at my stock '73 Tiger sitting on bike the motor is pretty much right on level. Just holding bike upright & letting shocks settle the motor is level.

I'd think you'd have to have a crazy amount of slope to interfere with oiling. All the choppers back in the late 60s had extended forks & motor was quite slopped. I used to take my TR6C hill climbing often & it never had a problem.

However... What I find on my Tiger is if the front end is up when tickling carb gas will run back into air cleaner, sometimes even before it comes out the tickler hole. That can mess with starting & also cause air cleaner fires if motor kicks back. My driveway is somewhat sloped & I have to be mindful of that. If I scoot bike around so it's level the bike doesn't want to stay on side stand properly. So I have to start it in garage, or roll it back by the front walk where my member photo was taken.

From your photo I'd expect with cyl & head on you'll be fine.

On a side note I think a skid plate from a '71-72 Trophy might fit your bike if you don't already have one.

Regarding going 70mph, I just did a 150 mile ride 2 days ago. 70 is not a problem. I find my motor is quite rough (vibration) at 59-62 & smooths out above 63. 65-72 is a little smoother yet. Getting up to 80 is starts shaking again. I'm running 20x46 sprockets. I think that would suit you well. If you're really going to do dirt, go 19 in front, but that will really spin up the motor at 70.

I most often ride 63-66 though. Depends on who I'm riding with & how they like to cruise. Getting into commuter lanes & interchanges I run 75 just to blend with traffic.

At 90 the motor is reving pretty high & I don't know it'd last long like that, but it pulls that speed easily. At 112 it feels like it's going to blow up. That was my limit, but the bike was still pulling faster.

Balance both front & rear wheels well. Heavy knobbies will make bike ride wiggly at 70 if not balanced. Some don't balance rear, but if rear wheel is very far out it can make bike feel odd.
Don
 
#7 ·
Thanks TR7RVMan - I was considering what sprockets to use.

The 'stock' 1982 Tiger Trail specifies an 18 tooth front sprocket and a 47 tooth rear which must have made for some interesting riding!

I have a nearly new 45 tooth rear which I was going to run with a 20 front which (as you said) should get the best out of the engine. I haven't acquired this yet so I'm open to sensible suggestions.

I already have a bash plate made to measure for the bike - just need to drill out some holes and polish it up and it's good.



Thanks again!

KitKat
 
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