View Full Version : '38 Junior Scout Timing

09-19-2010, 10:37 AM
I'm trying to set the timing on my "38 Jr. Scout. Looking thru the timing hole on the side of the motor, the only mark on the flywheel is what looks like a hole drilled in it. Any idea what this hole is indicating? I'm looking for a starting point to find TDC.
Information for the 30.50 engine is limited at best.
Any help would be greatly appreciated.

09-20-2010, 12:33 AM
As a starting point cant you remove a spark plug and look down to see the piston moving up. Or insert a pin or dowel into the plug hole and watch it when it reaches top. Some 2 stroke engines and I imagine other engines were timed with a dial indicator in the plug hole to see TDC.

09-20-2010, 02:49 PM
Thanks for the reply. I will try using a dial indicator. I'm sure my issue is somewhat simple. I can ge it to run but very very rough.
Is there any information for the 30.50 engine out there?
I really do like this machine and would like to get it back on the road. Will try to post some photos of it soon.
Thanks again!

09-20-2010, 07:29 PM
Hey John, did you do the intake manifold test? A leak there would explain a lot.

Here's what "Modern Motorcycle Mechanics" has to say regarding timing....


You may also want to check the online library. There could be some info there regarding the 30.50's

(I see the scan isn't the best. If there is anything that you are unclear on regarding the text just let me know and I'll type it our for you)

Tom Lovejoy
09-21-2010, 12:34 AM
Way to go Cory, good stuff. If you have not timed it before, I would pull the head to time it. I bet the drill hole in the flywheel is balancing related. Once you git top dead center, put some blueing on the flywheel through the timming hole and scribe a line for the future. Works pretty good, did it on mine about 20 years ago - still easily visable today. Lot's of folks, have intake leaks and are slow to relize it, think it's something else. More good advise from Cory.Good luck, those are neat machines.

09-21-2010, 03:25 PM
Guys, thanks for the good information and quick replys.
I am off to get some metal blueing today. I did not do a manifold leak test yet, I will. I may have put too much faith in the new PEEK seals, new manifold nuts and carb gasket.
It looks like the rear head is more accesable. When the engine was out of the frame I did measure 7/16 from the deck to top of the piston as stated in the "Handbook". Not to say the primary sprocket may have moved when I put the engine in the frame. I only installed new copper head gaskets while on the bench. I did not mess with the timing gears.
I can't begin to thank you guys enough for you input. I anything else comes to mind please post. I hope I can report back with good results.

09-22-2010, 09:07 AM
Exactly where is the "timing hole" you are looking through? Chiefs and 45 Scouts Did Not have a timing hole in the case until the early 40's. I can't imagine that the Jr. Scout would have either. There is a hole at about 10:00 that is for a case vent. Is this the hole you are using? Also, with no timing hole there will be NO marks on the flywheel. What I have done is set the timing and then put a mark on the flywheel visible through the Vent Hole.

09-23-2010, 12:41 AM
741 30:50's had a timing hole at top also and I was told that those cases were favored by racers when building a 45 for that reason to view timimg mark on flywheel.

09-23-2010, 05:48 AM
The timing hole I am refering to is at the bottom left case inline with the output shaft. There is also a drain hole 1 inch below it. The holes are 3/8" pipe thread.
The area on the case is machined flat. Would the top hole be used to observe oil level in the bottom of the engine?
I would expect to use it should the engine fill up with oil while sitting. Just a thought.
Again thanks to all for the help.

09-23-2010, 08:24 AM
That is the Oil Level hole. This engine has NO timing hole, however, as I said you could remove the head, or just play with it till you get it right and Mark the flywheel through that Oil Level Hole.