Any Mikuni expert around?

DrSweden
Profile picture for user DrSweden
Posts
6767
Joined
8/30/2008
Location
Stockholm SE
DrSweden
Edited Date/Time 2/28/2013 1:48pm
I'm about to buy a needle valve set because mine has started pissing, but having some issues to find a Yamaha dealer to spit out this part before the weekend. Seems Mikuni TMX 38 mm carb is used in more than the YZ125, should also be used in CRs CR125 and 250 2002-2003? The outer carb looks a bitt different in the pics though, anyhow seems I can find dealers that can find items for OEM Honda before weekend close by and I was thinking going for the needle valve set for that bike instead? Strange is that there's no needle valve set for the Honda do buy, here you have to buy the valve float separately no 2 (part with the rubber tip that stops the gas from pooring down in the bowl.

Strange question, probably out of luck...

Honda


Yamaha
|
xnationalwrench 2/26/2013 2:05pm
2/26/2013 2:05pm
The Yamaha needle and seat is reference #11 which is both parts (#4PE-14107-38-00). The Honda sells both pieces seperate ref #2 & #3. BTW Yamaha suggested retail is almost 1/2 the price of the Honda. Back in the day we used the needle & seat off of a Yamaha road racer (TD-2 or TR-2) because they had a higher flow.
pete24
Profile picture for user pete24
Posts
2733
Joined
10/20/2011
Location
Marlborough, MA US
pete24 2/26/2013 2:21pm
2/26/2013 2:21pm
see the oring on the #11 part? im betting thats the only part you need i replace a lot of those
DrSweden
Profile picture for user DrSweden
Posts
6767
Joined
8/30/2008
Location
Stockholm SE
DrSweden 2/26/2013 2:57pm
2/26/2013 2:57pm
Tnx guys, Yamaha is cheaper no doubt, but I will check that o-ring out tomorrow, no doubt.
xnationalwrench 2/26/2013 3:05pm
2/26/2013 3:05pm
Also check out the rubber tip of the needle sometimes it has some trash pressed into it. Put the tip between your thumb and fore finger and turn it several times.

The Shop

See All »
mynewcr250
Profile picture for user mynewcr250
Posts
681
Joined
10/22/2012
Location
CA US
mynewcr250 2/26/2013 7:34pm
2/26/2013 7:34pm
pete24 wrote:
see the oring on the #11 part? im betting thats the only part you need i replace a lot of those
this.

even on the flat slide tmx, it usually wasnt the needle or the seat it was the little o ring
DrSweden
Profile picture for user DrSweden
Posts
6767
Joined
8/30/2008
Location
Stockholm SE
DrSweden 2/27/2013 12:30pm
2/27/2013 12:30pm
Funny story, I call ALL shops around, none had them in store, one shop had a left over carb, but that piece was already gone. But that same guy gave me a tip of an old guy who actually was an Mikuni reseller in his private house. Went to that address and this 70+ old guy opens up, he had 15 min CZ from 60-73, some had GP air time on them, and he had one of these suckers in his drawer! So down to the garage in 30 and see if it fits, got an extra o-ring for the next time, since it's most likey the issue to start with.

Seems these issues rarely happens with bangers, and was more of a familiar problem with the smokers? How many of you had leaking carbs on your 250Fs? I had a few ones, but only on smokers, and on Thumpertalk this is a common Yamaha YZ issue?

Is it the oil in the gas?
xnationalwrench 2/27/2013 1:55pm
2/27/2013 1:55pm
DrSweden wrote:
Funny story, I call ALL shops around, none had them in store, one shop had a left over carb, but that piece was already gone. But...
Funny story, I call ALL shops around, none had them in store, one shop had a left over carb, but that piece was already gone. But that same guy gave me a tip of an old guy who actually was an Mikuni reseller in his private house. Went to that address and this 70+ old guy opens up, he had 15 min CZ from 60-73, some had GP air time on them, and he had one of these suckers in his drawer! So down to the garage in 30 and see if it fits, got an extra o-ring for the next time, since it's most likey the issue to start with.

Seems these issues rarely happens with bangers, and was more of a familiar problem with the smokers? How many of you had leaking carbs on your 250Fs? I had a few ones, but only on smokers, and on Thumpertalk this is a common Yamaha YZ issue?

Is it the oil in the gas?
The 4 strokes blow up before o-rings can rot.
mynewcr250
Profile picture for user mynewcr250
Posts
681
Joined
10/22/2012
Location
CA US
mynewcr250 2/27/2013 7:43pm
2/27/2013 7:43pm
DrSweden wrote:
Funny story, I call ALL shops around, none had them in store, one shop had a left over carb, but that piece was already gone. But...
Funny story, I call ALL shops around, none had them in store, one shop had a left over carb, but that piece was already gone. But that same guy gave me a tip of an old guy who actually was an Mikuni reseller in his private house. Went to that address and this 70+ old guy opens up, he had 15 min CZ from 60-73, some had GP air time on them, and he had one of these suckers in his drawer! So down to the garage in 30 and see if it fits, got an extra o-ring for the next time, since it's most likey the issue to start with.

Seems these issues rarely happens with bangers, and was more of a familiar problem with the smokers? How many of you had leaking carbs on your 250Fs? I had a few ones, but only on smokers, and on Thumpertalk this is a common Yamaha YZ issue?

Is it the oil in the gas?
i think its just time. friends have had these failures but we're talking 10-12 year old carbs.

depending on o ring composition they have different rates of compression set. its an eventual failure on anything that uses an oring to seal in my opinion.
DrSweden
Profile picture for user DrSweden
Posts
6767
Joined
8/30/2008
Location
Stockholm SE
DrSweden 2/28/2013 1:48pm
2/28/2013 1:48pm
mynewcr250 wrote:
i think its just time. friends have had these failures but we're talking 10-12 year old carbs. depending on o ring composition they have different rates...
i think its just time. friends have had these failures but we're talking 10-12 year old carbs.

depending on o ring composition they have different rates of compression set. its an eventual failure on anything that uses an oring to seal in my opinion.
True that. It's not like human cartilage that regenerate (at sometimes even that doesn't work). Time will work all of them down.

Post a reply to: Any Mikuni expert around?