Help reading plugs?

[wmazz]

Use the aluminum parts as a template, and the gaskets as just a visual reference.

If you replace the intake manifold/reed gaskets, use the spacer plate, so you don't
accidentally cut out the cross over tract.

Cut a bolt hole, insert a bolt, stretch out the gasket material and cut
another bolt hole. Cut as many bolt holes as possible before cutting
intake tract.

Bill M.

Be sure to replace the gaskets I pointed to in the attachment. They are standard
38mm carb gaskets.

 

[wmazz]

the stock is 115g, you could try a 95g spring

You should replace your cut springs.

Either replace them with a 95gr as suggested by Fastgtfairlane, or possibly the
stock 115gr springs and (2) 75 low jets. (I have never tried that myself, but it is
a safe change that should help starting, idling, and low end response)


Bill M.

 

[01jetsurfer]

is there a torq spec when putting back together the part that u pointed to on the first page? and also the carbs ? since i had them apart again and again and again i remembered this time to look at the jets and the low is 70 and high is 130. should i order different size jets or will those sizes work with my set up. as far as the screens go it didnt come with any i bought some and left them on the back of my truck and took off and they are lost to the freeway somewhere so adding thoose is not an option anymore. idk if i said but the needle and seets are 1.5 i ordered new ones but i got them from ebay so i took the ebay ones back out and cleaned and pollished the old ones to look new again and they deffently change the popoff i think they just seet a little better. ur right about the ebay needle and seets being not up to par. bill. i also put the 115 spring back in and it pop at 48 both carbs. im gonna order the 95 g springs and at the same time was wondering if i should get jets too. if so what number? thank you will post how it runs after i get it all back together.

 

[wmazz]

idk if i said but the needle and seets are 1.5 i ordered new ones but i got them from ebay so i took the ebay ones back out and cleaned and
pollished the old ones to look new again and they defiantly change the popoff i think they just seet a little better. ur right about the ebay needle
and seets being not up to par.

Just make sure you use the o-ring from the Mikuni rebuild kit for the seats.

16 ft-lbs for all the 8mm bolts. I like using a dab of Loctite 515 (or maybe 518)
gasket maker, or a little dab of 3Bond 1211, or a dab of ultra silicone on the
side of the threads (not on the ends). All of these are just a little better than
blue loctite.

I would `either run the 115gr springs with 75 low jets, or use the 95gr spring
with no changes to the jetting because it will richen the low end.

The Yamaha carbs are different internally than the aftermarket 38 sbn, and other
oem 38 sbn. That difference allows them to run with high pop-off and lean low
jets, and still perform as expected.

I don't know for certain, but I suspect the difference is for smog emisions and fuel
mileage. Smog emission testing was done at an idle, so all they needed to comply
was a lean low speed circuit. I mentioned mileage (gals/hr) because small differences
in the low speed/pilot circuit make big changes in mileage.

Learn how to tune your carbs with the "idle drop test". Rich pilot screws will hurt
top end performance.


Bill M.

Why did Klemm recommend changing the pop-off? If your engine started, idled,
and transitioned from low to high rpm, why change the pop-off?

 

[01jetsurfer]

thank you for all the advice and tips i read ur blog on the" idle drop test" a few times and printed it so i can bring it with me to the ramp when i get my ski in the water so its fresh in my head. hopefully today if i get my ski back together if not than tomorrow for sure. idk why it was suggested to change pop off it was running pritty good before i rebuilt the carbs the only issue this was after rifden it was hard to start but as we talked and, u suggested , it was a leak that was causing that. it only makes sence. thanks again.