ES 250/2 Carburettor

[liquidgold]

Am Working my way through a recently acquired Trophy that has been off the road since 1977. The Haynes book says the Carb. should be a 28N1-1 with a C5 needle and a main jet 107 and a float needle valve 18. The carb. I have is a 28N1-3 with a C3 needle main jet 120 and float needle valve 20.
Will this work OK or if not what is this carb. off? John

[Guesi]

The 28N1-1 was for the first model with 17,5 HP power.
The 28N1-3 was for the 19 HP version.

[liquidgold]

Thank you for your reply. Is there any way of identifying a 17,5 HP engine or is the power increase all done with the carburettor? The engine number is 4507664. John

[Guesi]

Yes, you can identify it.
The 19 HP version has an intake design on the cylinder like this:
https://www.guesi-motorradteile.de/inde ... 1/c/_/_/?_

The 17,5 HP version looks like this:

https://www.guesi-motorradteile.de/inde ... 8/c/_/_/?_

[liquidgold]

Thank you very much. Will have a look today. You are a mine of information. Regards John

[liquidgold]

Hi Guesi. It has the 19 HP version so will be interesting to see how it runs with the lower HP carburettor some time in the future. John

[Guesi]

You have the 28N1-3 carb. This is the right one for the 19 HP version, so no problem...

[liquidgold]

Yes you are quite right Guesi. I have so much going round in my head with this bike I am confusing myself. I am finding that it has been made up from more than one bike.
I really appreciate you taking the time to answer these questions and looking at your website you are obviously very knowledgeable on these bikes, so, this one puzzles me. The inlet manifold is marked ES 175/2, how is that different to a ES 250/2 manifold? Every thing seems to line up ok with no steps or restrictions to hinder gas flow. John

[Guesi]

The ES 175/2 had a 26 mm carb. The ES 250/2 had a 28 mm carb.
Maybe someone had widened the ES 175 intake to fit to an 28 N carb ?

[liquidgold]

Thanks again for the information.