The Zongshen TT 250 is Coming

[SpudRider]

Originally Posted by RedHawk47

So, I know little about carburetors. A question: I live at 5000 ft elevation and will be riding to 8000 ft, and maybe higher. What adjustment(s) should I make? Move the needle down to make it leaner? (There's less oxygen so I would think the mixture would be richer without changing things - is this right?) Or do I need a new needle?
How do I know if I have is right? Lots of test rides?

Yes, the fuel mixture will probably be rich at your elevations. You don't need a new jet needle. You experiment with different carburetor jets, take test rides, and zero in on the optimum jetting. Also, as others ride the same bike, you compare notes. In short order, people begin to agree on the best jet configurations for different elevations.

[SpudRider]

Originally Posted by Weldangrind

It's a clone of a Keihin. Keihin was Honda's choice for many years.

It remains to be seen if Keihin jets will fit the Keima. If not, I'd promptly switch to a Mikuni.

Originally Posted by fitze

You can get Keima jets what size do you need? And if the quote is correct
"The only thing you’ll need to do is add gas" You don't need to change the jets or the
carburetor and if you do flat side OKO not a knockoff Mikuni on a quality built Zongshen Engine.

At higher elevations you will probably benefit from choosing leaner jets. I'm confident CSC will stock different jets for this carburetor.

[rojo_grande]

I'm in the same boat as RedHawk, at 5,000 ft outside Denver and will be riding a lot at 8,500 to 12,000 ft. I'm sure I'll need to lean things out a bit. My first assumption is that the carb will be on the lean side to pass EPA testing and may be OK at 5,000 feet.

I did ask Ryan when I put the deposit down on the TT about carb jets. He indicated CSC would stock a number of jet options.

I'm on the RX3 Baja ride and will be hoping to haul a TT back with the Orange Blossom Special. I'll ask about suggested jetting options when I'm at CSC.

Rojo

[Weldangrind]

Watch the plug. If it turns black at 5000 feet, the first step is to determine where in the range it is lean; idle, mid-range, WOT or all of the above. A plug chop in each range will tell the answer. Once you have the answer, you can jet and move the circlip accordingly.

[DanKearney]

Originally Posted by SpudRider

The TT250 carb is definitely not a constant velocity (CV) carburetor. It is a Keima slide carburetor.

Thanks for that info Spud.

Cheers,

Dan K.

[SpudRider]

You're welcome, Dan.

[SpudRider]

CSC has posted yet another excellent tutorial regarding Clutch Cable Installation and Adjustment.

http://californiascooterco.com/blog/?p=20046

[SpudRider]

Egads! The excellent TT250 tutorials keep coming. CSC has posted two more maintenance tutorials for the TT250 at the CSC Blog.

TT250 Clutch Replacement is posted at the following link.

http://californiascooterco.com/blog/?p=20111



TT250 Oil Pump Replacement is posted at the following link.

http://californiascooterco.com/blog/?p=20127

[Wolftrax]

CSC is not only doing a great service for it's customers, but also for all owners of CG engines! I'm going to print these all out and voila, my service manual for my trip!

[SeerAtlas]

Originally Posted by SpudRider

Egads! The excellent TT250 tutorials keep coming. CSC has posted two more maintenance tutorials for the TT250 at the CSC Blog.

TT250 Clutch Replacement is posted at the following link.

http://californiascooterco.com/blog/?p=20111



TT250 Oil Pump Replacement is posted at the following link.

http://californiascooterco.com/blog/?p=20127

So from the pic, can I assume the counterbalancer is in fact year driven? If so, what is the small chain driving?

[CSCDude]

Originally Posted by SeerAtlas

So from the pic, can I assume the counterbalancer is in fact year driven? If so, what is the small chain driving?

Thanks for all the nice stuff you guys are saying. Steve is worried Gerry and I are going to ask for a raise.

The counterbalancer is gear driven. We thought about incorporating a chain drive for the counterbalancer, but Eagle Mike thought he might have a problem keeping up with new doohickey demand (you KLR guys will know what I'm talking about).

The small chain drives the oil pump. I just added that tutorial this morning.

Keep an eye on the CSC blog...Gerry just put the new larger-diameter front brake on my RX3, and I'll have a tutorial going up on front brake installation this weekend. I'm going to finish Moto Colombia this weekend, too. Lots of time on the keyboard these last couple of weeks.

[DanKearney]

Joe B.,

I was just looking at the TT250 Clutch Replacement tutorial. I noticed the info on cleaning the Centrifugal Oil Cleaner:



There's no mention in the turorial (http://californiascooterco.com/blog/?p=20111) of a service interval for cleaning this. Is it addressed in another turorial or in the service manual that comes with the TT250?

Cleaning the oil slingers was a must-do maintenance task on the old BMW airheads and could lead to engine failure if neglected, so I am curious how often this needs to be done. It does look much easier to do on the TT250 than the old boxers though.

Cheers,

Dan K.

[CSCDude]

Dan:

That's a good question. I'll have a good answer (and an update to the tutorial) by the time the bikes arrive.

There seems to be several opinions on this. One is that you don't ever need to clean it if you change the oil regularly and keep the strainer clean. Another is that you should clean it when you do a clutch replacement because you'll be in there anyway. And the third is that you should do it every 7500 miles, based on what Honda originally recommended for the CG125, which is kind of the grand-daddy for all of these engines (but guys who have played with those say they never found any contaminants in the centrifugal oil cleaner). We're talking to Zongshen about this now. And, of course, we'll keep an eye on this with our bikes, as we intend to rack up more than a few miles on them.

I'm sure others will have inputs on this question. We're eager to hear from everyone.

[pete]

Originally Posted by CSCDude

Dan:

That's a good question. I'll have a good answer (and an update to the tutorial) by the time the bikes arrive.

There seems to be several opinions on this. One is that you don't ever need to clean it if you change the oil regularly and keep the strainer clean. Another is that you should clean it when you do a clutch replacement because you'll be in there anyway. And the third is that you should do it every 7500 miles, based on what Honda originally recommended for the CG125, which is kind of the grand-daddy for all of these engines (but guys who have played with those say they never found any contaminants in the centrifugal oil cleaner). We're talking to Zongshen about this now. And, of course, we'll keep an eye on this with our bikes, as we intend to rack up more than a few miles on them.

I'm sure others will have inputs on this question. We're eager to hear from everyone.

When I bought the Honda CRF150F for the boy... I gave it a complete going over
steering head bearing/wheel bearing replaced ,swing arm/linkage etc..changed the oil & cleaned the centrifugal filter... It was clean , next to nothing in it , this is a 03 model that had not had any maintaince done on it ever I would say...So can't imagine the filter had ever been cleaned before...

PS... That Zongshen motor looks a bit better built inside than most other chinese bikes
I have been inside of.....





..

[DanKearney]

Originally Posted by CSCDude

Dan:

. . .I'll have a good answer (and an update to the tutorial) by the time the bikes arrive. . .

Thanks Joe.

Cheers,

Dan K.