150 and 200 2 stroke differences

[BQUICK]

say you have a late 80s 150.....are the only differences timing and carb sizes compared to a 200?
Exhaust manifold and muffers have same part numbers.

Not sure about reeds, this appears conflicting:

REED VALVE ASSY
UR 200

6E5-13610-00-00


REED VALVE ASSY
UR150/200

6G5-13610-00-00

[boscoe99]

Blocks are different. Carburetors are different. Reed valve assemblies are different.

The core part number for a particular part usually is the same for all engine models. That is, a reed valve assembly is part number ***-13610-XX-XX. With a 6G5 in front it is a reed valve assembly for the 150 HP model. With a 6E5 in front it is for an 175 or 200 HP model. The parts can be completely different from one another.

For instance a four stroke F150 piston has a core part number of 11631. So does a 150 two stroke. The piston are vastly different. One has a 63P prefix and the other has a 6R5 prefix.

[BQUICK]

How are the blocks different?

[boscoe99]

How are the blocks different?

Don't know. They have different part numbers so there is something different about them. Both the core block and the complete assembly. One carries a 6G4 prefix and the other carries as 6G5 prefix. Most surmise the difference is in the intake and exhaust port locations.

One thing I see that they use different cylinder heads as well.

[ausnoelm]

Part numbers can be tricky, some list a single part for both motors, simply because the one part will fit both, no problem, but in reality, it is the higher HP part, because if fitted to a 150, the 200 part functions fine, but, put a specific 150 part in a 200, then performance can be degraded, the example with the reeds shows this, the 200 reeds work fine in a 150, but the 150 reeds are ONLY suitable for the 150, get what I mean? I have seen this many times, people look at parts lists and there is nearly no differences, because only the higher HP parts are kept in stock if they are backward compatible, that's why trying to get more HP out of a common engine "family" is not always as straight forward as it seems (but sometimes it is of course) how many times have we seen "the only difference is the carb jets"?

[BQUICK]

The reason I ask is that a guy has a pair of 150s for sale and I have a bunch of 200 parts. Intakes, reeds, carbs, etc.
Thinking I could make them into 200s.

[pstephens46]

Hell, give it a shot. Make some videos for us.

[Captn Dave]

I think for late 80's motors you might be able to do that.

The 150 carbs have smaller diameter throats. The 175 and 200 carbs have larger throats and different jets between them.

In the 90's they started to add additional reeds to the 175's and 200's. Early 150's had the same reeds as the 80's motors and then later on they added the additional reeds.

Check the part numbers for the inlets of each and if the same I would try just swapping the carbs at first.

What's the condition of the shift shafts on the 150's?

[BQUICK]

Shift shafts are mint, as are the motor covers. They were stored years ago.

I'm thinking as 200s dry up swapping 200 stuff over to 150s is going to be a viable option for those of us who won't give up on these great old 2 strokes.