I'm confused by H1 numbers, please help!!

I'm confused by H1 numbers, please help!!

Postby sean250766 » Fri Oct 10, 2014 10:40 am

Please bear with me as I'm quite new to H1's. But I mangaed to pick myself up a nice fairly standard 1974 H1E thats not been on the road since 1980. Got it running nicely and virtually ready for MOT then register. From what I can see the frame number is a 74 H1E, and the headstock decal says dec 73, so thats ok, but the engine number is KAE 23695, which when I've looked it up is a 71 H1A, but as you can see from the pic it doesn't look like a H1A engine.. any ideas or am I way off with dating by the engine number?
Thanks
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Re: I'm confused by H1 numbers, please help!!

Postby Scouse » Fri Oct 10, 2014 4:54 pm

The later engines where rubber mounted & had re circulation valves fitted to the front engine, they are at the front on the bottom of the cases

All clutch covers fit all models, what ignition system does it have ?
What does the other side of the engine look like?

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Re: I'm confused by H1 numbers, please help!!

Postby Scouse » Fri Oct 10, 2014 4:57 pm

This page might help you
http://3cyl.com/mraxl/partid/partid.htm

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Re: I'm confused by H1 numbers, please help!!

Postby RB » Fri Oct 10, 2014 5:27 pm

Gary is correct, your engine is 74,000 numbers out, your cases came from an August 1970 H1a
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Re: I'm confused by H1 numbers, please help!!

Postby sean250766 » Fri Oct 10, 2014 5:52 pm

Thanks, I'll take some more pictures tomorrow of the engine and post them. Its on electronic ignition with a single box cdi. I have a H1F engine, that looks identical and thats why the engine numbers threw me. Could it be that just the engine cases have been changed at some time?? Are they interchangeable with the later ones?
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Re: I'm confused by H1 numbers, please help!!

Postby ja-moo » Fri Oct 10, 2014 8:03 pm

Yes, the outer cases can interchange.
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Re: I'm confused by H1 numbers, please help!!

Postby sam » Fri Oct 10, 2014 9:11 pm

RB wrote:Gary is correct, your engine is 74,000 numbers out, your cases came from an August 1970 H1a


Perfect Mismatch :lol:
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Re: I'm confused by H1 numbers, please help!!

Postby Scouse » Sat Oct 11, 2014 6:54 am

sean250766 wrote:Thanks, I'll take some more pictures tomorrow of the engine and post them. Its on electronic ignition with a single box cdi. I have a H1F engine, that looks identical and thats why the engine numbers threw me. Could it be that just the engine cases have been changed at some time?? Are they interchangeable with the later ones?

You need to play a game of spot the difference

If you look at the F engine top top front mount you'll see 2 metal sleeves, this is part of the rubber mounting system
Now look at the same mount on the engine on your bike, you'll just see the engine bolt.

At the front of the F cases on the bottom you see 3 check valves

Image

Your early cases won't have these

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Re: I'm confused by H1 numbers, please help!!

Postby ja-moo » Sat Oct 11, 2014 7:10 am

Kind of a bummer, the rubber mounts sure make for a much smoother ride.........
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Re: I'm confused by H1 numbers, please help!!

Postby sean250766 » Sat Oct 11, 2014 4:00 pm

Thanks guys, I did some more investigating yep the cases have obviously been changed for an earlier set, but the good news is the engine has done virtually nothing since being done. The underside of the engine is like brand new, so I've whipped the heads and barrels off today to have a look, and again its like brand new in there, no carbon, no scoring or marks on the bores, nothing but honing marks.
So I gues its not so good with it having the wrong cases for the year of the bike, but great news in that the engine must have had a recent rebuild. Although it goes with the wrong paint scheme for the bike.. I'll have to start calling it a bitsa :lol:
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