TBR7 upgrades and problems

[paulsstag]

Just wanted to touch bases on my TBR7. First off i live at 600ft and am riding @ 6000- 8000 ft so pretty high. Bike shows 480 miles but the odometer over reads big time and it's a lot closer to KM so i would say closer to 300 miles.

I've been riding on the bone stock carb up until now and even at these elevations she is running lean, actually runs crisper and idles better at 8000 ft.

So i pulled my mikuni (clone?) apart and changed the main jet from the factory 100 to a 105 as a guy i met a while back had told me that was what he was running on his hawk in this area ( also got me looking at these china bikes). pilot jet was a #20 and air screw was out 1 1/4 turns stock. i left the needle clip in the center position and took off my original carb and fitted the VM26.

I turned out the air fuel screw another 1/4 turn for a good idle ( now @1 1/2 turns) .

Bike is running much better and smoother . So if this helps when i rode from my house up to the town of Pinos Altos its a 6 mile run with an elevation gain of 1000 ft. With the stock carb i could barely do the speed limit (45 and 50) and the last stretch is very steep ( maybe 8% ?) at which time i'm down to 4 th gear and can barely hold 35.

After carb change it just cruises up the hill at posted speed limits with throttle to spare and the last stretch 40 mph in 5th but opening the throttle all the way does not change the speed.

Right, yesterday i changed out the main jet to a 108 and the bike is better, speed limit no problem and the last stretch 45 mph and when i opened the throttle the bike started to accelerate( be it slowly). i'm going to call this good for now.

Info to consider:
gearing change from 15/46 to 17/46.
Bone stock intake system and filter.
Bone stock exhast including cat and muffler.
TBR's come with more street type tires than hawks.(17r/19f).

So problems so far, Speedo is not accurate and odo is closer to km than miles.

I've been riding on some really rocky and rough terrain and the bike is pretty tough in my opinion and i think the 17/19 rim combo makes them more durable than the hawks (shorter spokes ?). But i have now blown the factory rear shock, it is now a spring on a stick with zero damping.

I weigh 180 so with my gear on i'll say 200 ready to ride. I'm not moto-xing or jumping but certainly carrying some speed over rough terrain to keep up momentum for some of the very steep washed out trails i'm riding on.

I've lost the high beam on the headlight bulb (still have low beam) and my back running light is dead but i still have the rear brake light. I was going to upgrade to led's anyway.

Fuel cap leaks out the top when tank is full so i'll see if i can do something about that.

Will remove the rear shock assy to see how long it is and get a replacement.

So some pictures and video. Coming up.

[paulsstag]

Some pictures and video with me and my dog , this is his very first ride and he loved it.

[paulsstag]

[paulsstag]

[kingofqueenz]

Hey Paul, I have the same bike (as of April) running bone stock carb and 15 tooth front sproc.

Did I understand you correctly in that you swapped carbs to a mik clone or are you saying you changed the jetting on the stock carb?

I'm thinking of ordering the carb kit from ebay

Mike

[paulsstag]

Originally Posted by kingofqueenz

Hey Paul, I have the same bike (as of April) running bone stock carb and 15 tooth front sproc.

Did I understand you correctly in that you swapped carbs to a mik clone or are you saying you changed the jetting on the stock carb?

I'm thinking of ordering the carb kit from ebay

Mike

Hi Mike , i took off the stock carb and i have never even opened it up. I left it like that so if ever i have problems i can bolt it back on as a reference point. i bought a VM26 replacement plus jets(total under $50) to tinker with and after reading many posts about these carbs with some having #20 pilot jets and some #40 pilot jets i wanted to open mine up to see what it had.

It is most certainly a worthwhile change IMHO, It seems the factory main jet in the stock carb is a #88 which is very very small. Part of the reason i could run the stock carb is the elevation at which i live (6000 ft) so it probably is only a good reference point for people living in colorado etc but i wanted to put it out there anyway.

If you live at lower elevation then the change ( of carb ) must be worthwhile.

I'm not trying to say my bike is like a rocket ship now but the change is very noticable .

Paul

[NzBrakelathes]

Originally Posted by paulsstag

Hi Mike , i took off the stock carb and i have never even opened it up. I left it like that so if ever i have problems i can bolt it back on as a reference point. i bought a VM26 replacement plus jets(total under $50) to tinker with and after reading many posts about these carbs with some having #20 pilot jets and some #40 pilot jets i wanted to open mine up to see what it had.

It is most certainly a worthwhile change IMHO, It seems the factory main jet in the stock carb is a #88 which is very very small. Part of the reason i could run the stock carb is the elevation at which i live (6000 ft) so it probably is only a good reference point for people living in colorado etc but i wanted to put it out there anyway.

If you live at lower elevation then the change ( of carb ) must be worthwhile.

I'm not trying to say my bike is like a rocket ship now but the change is very noticable .

Paul

The stock carb is as tunable as the mikuni - just a little effort needed to open the 3 screw and brass plug covering the adj mix screw

[paulsstag]

Originally Posted by NzBrakelathes

The stock carb is as tunable as the mikuni - just a little effort needed to open the 3 screw and brass plug covering the adj mix screw

I agree with you 100%. in my case i probably just needed a bigger main jet and possibly a needle shim . I was just lazy to cut slots in the stock float bowl and drill out the plug for the air mixture screw. However doing it this way if things did not go according to plan with the stock carb your bike might be down until you can figure it out . Mine was a swap and go.

Also about the pumper carb, I believe Megadan is on his game about it being the best choice and it is good to know how to get the best out of these little bikes. I ,for the moment , just wanted it to run a little better than with the stock carb, but at the same time did not want to mess with the original carb.

I'm sure as time goes on i will probably follow what megadan and jerry have done to their bikes , porting , compression increase, pumper carb and better intake and exhaust etc. Truth is without guys like them how many would try to improve their rides?

I also appreciate people like you for keeping your finger on the pulse so to speak and put together viable replacement part options. Some of the stuff you have seen where you live will probably boggle my mind .

[NzBrakelathes]

There’s very little difference between stock “correctly” tuned carb or “mikuni clone” correctly tuned.

For the money of a mikuni and jets you’re well on the way to a pumper carb and first tune kit- just my thoughts and yes somewhat bias as I do sell both pumper n first tune sets.
Main thing is to consider and judge measured results.
The thing is there are no numbers to compare so really no facts as to which is better a stock well tuned carb, a mikuni clone with genuine jets or a pumper carb etc
Everyone likes there choices but what measure or facts do we base it from?

Just being as fair as I can and saying regardless what option you choose over another and done correctly everyone is happy but some spend more then others getting there.

I’m in CT USA next week and I’ll bring some stock with me cause I can’t send from China while I’m in the USA lol.

[Megadan]

Originally Posted by NzBrakelathes

There’s very little difference between stock “correctly” tuned carb or “mikuni clone” correctly tuned.

For the money of a mikuni and jets you’re well on the way to a pumper carb and first tune kit- just my thoughts and yes somewhat bias as I do sell both pumper n first tune sets.
Main thing is to consider and judge measured results.
The thing is there are no numbers to compare so really no facts as to which is better a stock well tuned carb, a mikuni clone with genuine jets or a pumper carb etc
Everyone likes there choices but what measure or facts do we base it from?

Just being as fair as I can and saying regardless what option you choose over another and done correctly everyone is happy but some spend more then others getting there.

I’m in CT USA next week and I’ll bring some stock with me cause I can’t send from China while I’m in the USA lol.

There is no sellers bias here. The pumper carb is the only true "upgrade" in terms of any real measurable performance benefit. I wish I had a one stop shop when I bought mine., and I will recommend it over the mikuni for that reason.

[GronkFries]

Originally Posted by Megadan

There is no sellers bias here. The pumper carb is the only true "upgrade" in terms of any real measurable performance benefit. I wish I had a one stop shop when I bought mine., and I will recommend it over the mikuni for that reason.

I'm going to mess with my stock carb to gain some experience, but I can imagine a nice accelerator squirt would be advantageous. I don't think I've ever owned a bike that didn't have a pump. The stock carb on the TBR7 has an ok initial brap to it but poorly transitions to wide open power at such a disappointing level. The jet change that I'm doing today will benefit but I have a feeling I will be longing for that fine spray of ethanol free fuel at some point.

[paulsstag]

Originally Posted by GronkFries

I'm going to mess with my stock carb to gain some experience, but I can imagine a nice accelerator squirt would be advantageous. I don't think I've ever owned a bike that didn't have a pump. The stock carb on the TBR7 has an ok initial brap to it but poorly transitions to wide open power at such a disappointing level. The jet change that I'm doing today will benefit but I have a feeling I will be longing for that fine spray of ethanol free fuel at some point.

When you do your stock carb let us know if it is a #88 main jet and how many turns out the fuel mixture screw is stock and how many turns you need to make it run well. Also let us know if you shim the needle or replace it with an adjustable one ?
good luck.

[NzBrakelathes]

Originally Posted by paulsstag

When you do your stock carb let us know if it is a #88 main jet and how many turns out the fuel mixture screw is stock and how many turns you need to make it run well. Also let us know if you shim the needle or replace it with an adjustable one ?
good luck.

Check online same as hawk
It’s been shown over and over again as it’s all genetic

[GronkFries]

Originally Posted by paulsstag

When you do your stock carb let us know if it is a #88 main jet and how many turns out the fuel mixture screw is stock and how many turns you need to make it run well. Also let us know if you shim the needle or replace it with an adjustable one ?
good luck.

It is a #88 jet, and stock mixture was a turn and a half or so. Maybe less, I can't remember exactly. And yes, like nzbl said 2 to 2.5 turns out seems to be best for me so far. I ordered his kit didn't see any high speed jets (I might have lost them so I ordered it again), so it remains sluggish powerwise for now. The 17 tooth sprocket makes a huge difference and that was worth the money alone.

I will be tossing the stock needle and using the adjustable when the jet comes in.

[NzBrakelathes]

My thinking is use first tune kit learn stuff about carbs
Then you can upgrade later to a pumper carbs first tune kit relates etc
That is my thoughts n part supply resining and I don’t want to bother offering a mikuni for that reason
There’s my thoughts n the ppl can choose etc all in my eBay store etc
Welcome to suggest what should be in the set but I’m pretty sure I have it pretty right