Vintage Dirt Bike Q & A

Hello everyone !

I am new french guy in this forum. First of all I would like to congratulate te webmaster for the quality of this website !!!

I am restoring a 1977 CR 125 at present time. Since these models has no reed cage and provide top end power only, I am quite interesting to add a GEM reed cage on my elsi .

If anyone has some experience about this GEM reed cage, I would appreciate to get your opinion and your advice .

Thanks in advance !

Thierry [/img]

Hi everyone !

So no one can provide any opinion or information ????

Is it because I am french ???

....

I don't bite and I am polite ...so don't be afraid !

I also have a Gem reed valve that I want to install on my 75 CR125 and would like info on its installation. Does anyone have an instruction sheet they could scan or advice from their Gem reed valve installation experience they could share??
I expect that the rear of the piston must be cut. Should the 30 year old reed petals be thrown away and modern reeds used?
How does engine performance change?
Thanks.
Mark (from Canada, a bilingual French/English country!!!)

The GEM reed on that engine runs OK, it does help the low end some, but it hurts the top end a little. If you do the mod you pretty much ruin the cylinder and can't go back to a piston port. I may have the instruction sheet, email me privately and I will look for it.

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Sam Alexander

1974 Honda CR250M
1976 Honda CR250
1974 Maico MC440
1974 Maico MC250
1977 Maico AW400

Bonjour Mark! Hello Sam !

(Mark, parles tu français ? )

Thank you very much for your reply . I was about to cry.... I am glad to see I am not alone to think about GEM reed cage...

I will email privately to the dear Sam . I am very interesting to see instruction sheet !

Mark, my first idea is the same like yours. The piston should be cut a little bit in order to let the intake port do a longer job

I am also wondering how we arrange the situation concering the air boot .... if the original is kept, it means it should be tighted a lot at the back side .Mark how do you think ? do you have a special air boot or not ?

Sam is perfectly right concerning the cylinder "ruinning". Actually the reed valve need some clearance at the entrance of the cylinder. So a milling job must be done ...


Sam, when you say "hurt a little the top end"....do you mean it decrease the top end power ??? Is it really noticeable or is it just a small feeling ?

In others words, dear Sam, if you were in my position, would you install or not the gem reed cage ?

Thanks in advance

Thierry

The top end power will go a little flat with that reed. If you are a Novice rider, or a slower intermediate rider you may benefit from that reed setup, if you are a fast intermediate or expert level rider then the original piston port configuration is the best. We do modify the cylinders for the faster riders and get even more top end out of them. You have to realize that a fast rider on one of those bikes hardly ever shuts off the throttle and the engine is revved very hard.

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Sam Alexander

1974 Honda CR250M
1976 Honda CR250
1974 Maico MC440
1974 Maico MC250
1977 Maico AW400