450 Scrambler /jupiter project

[john jupiter]

Well.... She runs... Sometimes.. Had continuous problems getting it to start consistently, a few backfires and then discovered i had air actually coming out of the carb(the wrong way).. I think the timing is wayy off.. Took bevel drive cover off any the timing marks are not even close to being lined up. I guess i'll need to do some real wrenching here which should be interesting...
Any suggestions for a detailed repair manual that will help???.
I'll post pics as i go through this bevel beauty.
Thanks
John

[DewCatTea-Bob]

" Had continuous problems getting it to start consistently, "

____ DUKEs with the square-slide type carb usually start-up quite nicely, with the choke-lever pulled-back, (just opposite of a real 'choke' !).
Perhaps you haven't gotten the hang-of that down yet ?


" a few backfires and then discovered i had air actually coming out of the carb(the wrong way).. I think the timing is wayy off.. "

____ That's less common with Duke-models which employ the milder scrambler-type camshaft, but still doesn't mean that the timing is off. _ Could be that the intake-clearance is a bit tight.


" Took bevel drive cover off any the timing marks are not even close to being lined up. "

____ You're jumping to conclusions ! ... If those timing-marks were indeed misaligned, then the engine would likely never be able to run, even if you could still get some compression to occur.
Those bevel-gear timing-dots will only line-up every ten TDCs, so keep turning-over the engine (up to 4 compression-strokes), until those timing-marks finally align.
If you still can't get them to ever line-up, THEN you can conclude that that timing is off mark, (however that's quite unlikely to be the case!).


" I guess i'll need to do some real wrenching here which should be interesting... "

____ Why, what were you considering ?


Hopeful-Cheers,
-Bob

[john jupiter]

Bob,
Truth be told, this is my first kickstart so i cant rule out that i havent quite got the hang of it. I can tell you that ive had it start 3 times in 5 kicks and then couldnt get it running again for 45 minutes..
Compression seems to be VERY high, im 190lbs and i have a hard time getting the motor to turnover sometimes.. And im not babying it by any means.
When it took off the valve covers last night, the gaskets came off so easily im thinking it had just be worked on by previous owner.. what was i planning? Well i was going to take it apart and make sure everything is thw way it should be to the best of my ability before trying to start it again. .
I'll rotate engine 4or 5 times as your suggesting ans see where im at.
Ive got a compression guage, will check to make sure i dont have a high compression piston in it.
Is there an easy way to check the cam while ive got the covers off?
Thanks
-john

[machten]

Are you using the decompression lever? The 450 springer is a hard kick without it.

Kev

[DewCatTea-Bob]

By: JohnJupiter...
" I can tell you that ive had it start 3 times in 5 kicks and then couldnt get it running again for 45 minutes.. "

____ I recall that one or two others here have experienced that exact-same occurrence ! _ Hopefully one of them will see this & tell us how things went-forth from their like-issue !
My guess is a wet spark-plug. _ Have you tried replacing the plug with a fresh one, when that issue happens ?


" Compression seems to be VERY high, im 190lbs and i have a hard time getting the motor to turnover sometimes.. "

____ That ought confirm that the bevel-timing is not off, cuz the compression would be relatively weak or nonexistent otherwise.
__ If you don't have your compression-release set up to work properly, then you can try putting the trans in-gear & roll backward until you feel the compression-resistance, then put back in neutral and kick-through,, so as to get the crankshaft-flywheels to help your effort to spin the engine past the next comp.TDC and get started easier without so much effort.


" When it took off the valve covers last night, the gaskets came off so easily im thinking it had just be worked on by previous owner.. "

____ Original-stock gaskets usually stick to only one surface or the other, (I always put them so they will end-up sticking to the covers). _ If those gaskets fell-loose/off from both surfaces, then they are either aftermarket-type gaskets or you're right that they were recently installed.


" I'll rotate engine 4or 5 times as your suggesting ans see where im at. "

____ Then you should see those timing-dots line-up before the 5th compression-stroke !


" Is there an easy way to check the cam while ive got the covers off? "

____ Well what do you hope to check about it ?
I guess you could shine a light through there above the cam and then see if the lobes look nice & shiny (and hopefully not badly scored-up).


Hopeful-Cheers,
-Bob

[Teckhardt]

This all sounds very familiar. My 450 behaved in a similar way before I tore it apart.

It would start on the second kick cold but would not stay running w/o choke. Soon as you put it in gear it would die. No luck getting it started again when warm...

I never did sort it out before I tore it down. Will be interested to hear what is going on.

[john jupiter]

Btw i did not have the decompression lever set up. will have to get that taken care of.
The bevel gears did line up! Rookie mistake, thanks for the information on that one Bob!

In regards to the cam, i was hoping to find a stamp on the end or something to identify and confirm that it is a stock cam or not.

I just checked the intake clearance with a feeler gauge when there was no pressure on the rocker arm and it was .003 which i think is within spec. However i didnt use a timing wheel to make sure it was at proper degrees..
The exhaust valves tight and i cant get a .002 feeler in.. What is the easiest way to adjust this? Do i need a special tool?

Im going to try and make a tool since i dont have a timing wheel or timing needle.
Do you know what size thread on the end of the crank is so i can try and make something that will work?

-john

[DewCatTea-Bob]

" In regards to the cam, i was hoping to find a stamp on the end or something to identify and confirm that it is a stock cam or not. "

____ The intended method for doing that is to look at the tip of the cam (behind the bevel-cover) and see the cam's color-code which was originally merely painted-on. _ However the paint is usually washed-away by 2000-miles more or less. _ And the White paint-code for Scrambler-cams often takes-on some degree of tan from the oil.
__ A firm way to identify the model of a cam is to measure it's lobe-lift, but that may not be required to be fairly sure...
If you can post a pic like that seen here: viewtopic.php?f=3&t=582&start=10#p3770 , then I can confirm whether or not it's a WideCase-SCR.cam.
To get that shot of the camshaft's left-end, remove the four Allen-screws securing the '450' camshaft-bearing support-cover.
Then use a thin rod (longer than the camshaft), to insert through the center of the camshaft (from the bevel-end/side), to the opposite-end and lightly tap it until the bearing-support/cover gets knocked outward a bit over 1/4-inch, then grab the support/cover by hand & twist out & off.


" I st checked the intake clearance with a feeler gauge when there was no pressure on the rocker arm and it was .003 which i think is within spec. However i did use a timing wheel to make sure it was at proper degrees..
The exhaust valves tight and i cant get a .002 feeler in.. "

____ The valve-clearances are to be checked at 'comp.TDC', and ya really don't need any kind of "timing wheel" since ya know you're at the correct TDC when those bevel timing-dots are directly-aligned !
So if you hadn't noted that detail when you took your clearance-measurements, then check them again and report your actual valve-clearances.
They ought to be between .002 & .004" for intake, and .003 & .005" for exhaust, (but up to an extra 2-thousandths more, is close enough).


" What is the easiest way to adjust this? Do i need a special tool? "

____ For the time being, I'll just say that this subject has been well covered elsewhere in other related-threads. _ If you can't find such, then I'll later see if I can insert another link for you.
__ Do you already have a source for alternate v.shim-caps?


" Do you know what size thread on the end of the crank is so i can try and make something that will work? "

____ This has also been well covered before ! _ If you can't find the thread covering the topic, let us know, and then I'll get-around to providing still another link for you.
__ Thread-size is 8x1.25mm.


Hopeful-Cheers,
-Bob

[john jupiter]

beveldrive.jpg

frontenginecover1.jpg

[john jupiter]

some timing mark pictures below.

The gear with 2 alingment punches, that sits bewtween the crank and the mechanical advance/points shatf gear was off by several teeth. I have pull it out and aligned it properly. Any thoughts?

Curious on the gear attached to the mechanical advance and points.. it seems to have a dot AND a line on it. what is the significance?

I can now get all 8 alignment marks to line up... or almost. If i get the 4 timing gear alignment marks perfectly meshed and lied up the bevel gear marks are a tick or so behind and need further engine rotation to have their marks line up. I guess due to the gear ratio, once the bevels are lined up the timing gears are a half a tooth out of mesh. The pictures sort of show this. Is this normal or was the engine assembled incorrectly at some point?

lowergears 1.jpg

lowergears2.jpg