CSC TT250 slightly-missing

[jerhomey]

So I have about 80 miles on my new TT250 and overall its running decent, however sometimes when it seems after its warmed up when going high rpm on 3-4 it wants to kind of miss or fight back a bit i guess you could say. I also have to give it throttle for about 40 seconds or so when i first start it in about 70-80 degree weather , seems to idle fine after its warmed up.

Is there anything simple that I could try to smooth that out ? I saw someone mention that I live in ohio and maybe the bike is jetted for California emissions ? Its all stock and i haven't touched a thing so just looking for some advice. Ill prob break down and get this carb eventually

https://www.amazon.com/dp/B07CN36W65#customerReviews

but was just curious if maybe air mixer or something could help , Im enjoying the bike so far!

Thanks
Jerhomey[/LIST]

[Megadan]

So before we delve into the carb tuning side of things, I have to ask. Did you check/set the valve lash yet?

I am not 100% sure on the TT250 if they actually set this when the bike is new, but almost every other CG powered bike comes with the lash set to 0, and sometimes even tight. This will lead to running issues once the engine is hot because the valves will not seal correctly, and can potentially lead to burned valves and valve seats if left unchecked long enough.

[jerhomey]

Originally Posted by Megadan

So before we delve into the carb tuning side of things, I have to ask. Did you check/set the valve lash yet?

I am not 100% sure on the TT250 if they actually set this when the bike is new, but almost every other CG powered bike comes with the lash set to 0, and sometimes even tight. This will lead to running issues once the engine is hot because the valves will not seal correctly, and can potentially lead to burned valves and valve seats if left unchecked long enough.

Megadan

No sir i have not touched a thing other then removing the stickers and using the electric start , lol

Im assuming i can buy one of those fancy little valve tool kits to check all that ? I have never done it before but i have watched some youtube videos on checking valve clearence.

Thanks !
Jerhomey

[Megadan]

Originally Posted by jerhomey

Megadan

No sir i have not touched a thing other then removing the stickers and using the electric start , lol

Im assuming i can buy one of those fancy little valve tool kits to check all that ? I have never done it before but i have watched some youtube videos on checking valve clearence.

Thanks !
Jerhomey

You don't need any fancy tools really. CSC has a good article on the valve checks/services for your bike as well. You shouldn't have to remove the tank or any plastics though. You can remove the valve cover from the right side of the bike with a little maneuvering.

https://www.cscmotorcycles.com/check...lve-adjustment

[Choco]

Originally Posted by jerhomey

So I have about 80 miles on my new TT250 and overall its running decent, however sometimes when it seems after its warmed up when going high rpm on 3-4 it wants to kind of miss or fight back a bit i guess you could say. I also have to give it throttle for about 40 seconds or so when i first start it in about 70-80 degree weather , seems to idle fine after its warmed up.

Is there anything simple that I could try to smooth that out ? I saw someone mention that I live in ohio and maybe the bike is jetted for California emissions ? Its all stock and i haven't touched a thing so just looking for some advice. Ill prob break down and get this carb eventually

https://www.amazon.com/dp/B07CN36W65#customerReviews

but was just curious if maybe air mixer or something could help , Im enjoying the bike so far!

Thanks
Jerhomey[/LIST]

I got my bike around 2 weeks ago and i had the same problem. I had to hold the throttle(no choke) for about 25seconds on my first start.
I did a couple mods on mine but at 180miles i decided to adjust my valves. I did my valves 2 days ago and i start it right up now it stays on by itself (first start)without having to hold the throttle (also no choke) weather around 70. I recommend you do your valves. Once you change your jets you also notice some increase and you could go higher on rpms. Yes i couldnt wait to break mine in lol

Check out motocheez videos on how to do it. Make sure you are on compression stroke. i messed up the first time(i had to re do it the next day once to let it cool)
Csc shows tt250 should be .04 and .07mm

[jerhomey]

Originally Posted by Choco

I got my bike around 2 weeks ago and i had the same problem. I had to hold the throttle(no choke) for about 25seconds on my first start.
I did a couple mods on mine but at 180miles i decided to adjust my valves. I did my valves 2 days ago and i start it right up now it stays on by itself (first start)without having to hold the throttle (also no choke) weather around 70. I recommend you do your valves. Once you change your jets you also notice some increase and you could go higher on rpms. Yes i couldnt wait to break mine in lol

Check out motocheez videos on how to do it. Make sure you are on compression stroke. i messed up the first time(i had to re do it the next day once to let it cool)
Csc shows tt250 should be .04 and .07mm

Well that makes me feel better knowing yours is about the same age as mine and similar problems that you were able to resolve. I was reading through the CSC walkthrough that Megadan posted and it seems pretty straight forward. I ordered a 45tooth rear sprocket yesterday and might go with the supermoto wheels too for the summer so , i might wait until i get it all delivered and have a fun saturday wrenching lol.. appreciate the feedback makes me feel better.

On a side note have you changed your oil yet ? and if so what did you go with.

Thanks
jerhomey

[jerhomey]

Originally Posted by Megadan

You don't need any fancy tools really. CSC has a good article on the valve checks/services for your bike as well. You shouldn't have to remove the tank or any plastics though. You can remove the valve cover from the right side of the bike with a little maneuvering.

https://www.cscmotorcycles.com/check...lve-adjustment

Is that common to have to check valves that early ? or maybe they just didnt set them right to begin with ? just curious or is it just one of those random things ?

Thanks
jerhomey

[duck9191]

Originally Posted by jerhomey

Is that common to have to check valves that early ? or maybe they just didnt set them right to begin with ? just curious or is it just one of those random things ?

Thanks
jerhomey

They are almost always at zero clearance from the factory. No ones really indicated if CSC takes the time to gap them as part of assembly but i would guess they don't.

[jerhomey]

Originally Posted by duck9191

They are almost always at zero clearance from the factory. No ones really indicated if CSC takes the time to gap them as part of assembly but i would guess they don't.

Thanks duck9191!! Makes sense ! well 3 people telling me to check the valves so i think i should lol

[Choco]

Originally Posted by jerhomey

Well that makes me feel better knowing yours is about the same age as mine and similar problems that you were able to resolve. I was reading through the CSC walkthrough that Megadan posted and it seems pretty straight forward. I ordered a 45tooth rear sprocket yesterday and might go with the supermoto wheels too for the summer so , i might wait until i get it all delivered and have a fun saturday wrenching lol.. appreciate the feedback makes me feel better.

On a side note have you changed your oil yet ? and if so what did you go with.

Thanks
jerhomey

I think you should be good once you adjust them. Again just make sure you are on compression stroke.
I havent changed my oil yet but i bought this oil i will be changing soon
https://www.amazon.com/Maxima-349128.../dp/B000GU7LK6
After breakin and after im done with this oil i will switch to full synthetic.
You should change your jets too it really makes a difference

[jerhomey]

Well I Finally got around to getting the Valves checked and while it took me a second to get the hang of it etc i think i did a pretty good job of getting it set and i also turn the idle adjustment up as well and the bike seems to start better and idle better overall. However I drove it to work today about 18 mile trip and it still wants to bog down in higher RPMS on 4th and 5Th Gear. So what would be the next logical step ? I ordered a Jet kit from CSC but they are on back order for 2 weeks.

[2LZ]

How many miles? They change big-time as they break in.

[jerhomey]

Originally Posted by 2LZ

How many miles? They change big-time as they break in.

I think i just hit about 200 on my way in to work somewhere between 180 and 200

[Choco]

Originally Posted by jerhomey

Well I Finally got around to getting the Valves checked and while it took me a second to get the hang of it etc i think i did a pretty good job of getting it set and i also turn the idle adjustment up as well and the bike seems to start better and idle better overall. However I drove it to work today about 18 mile trip and it still wants to bog down in higher RPMS on 4th and 5Th Gear. So what would be the next logical step ? I ordered a Jet kit from CSC but they are on back order for 2 weeks.

I ordered these for my bike once i changed the main yet to a 110 it made a big difference
https://www.amazon.com/gp/aw/d/B017S...b_b_asin_title

[Megadan]

Originally Posted by Choco

I ordered these for my bike once i changed the main yet to a 110 it made a big difference
https://www.amazon.com/gp/aw/d/B017S...b_b_asin_title

If it were me, I would go this route over the cheap ebay/Amazon jets

https://www.jetsrus.com/a_jets_by_ca...und_28-xxx.htm

those are the correct jets for the Keihin clones like the one found on the TT250. At the very least, order the OEM equivalents if you don't want to shell out for the real deal. They will still be more accurate than the cheap kits from ebay and amazon.

Obviously the jet kit that CSC sells has a pilot jet and a better idle mixture adjustment screw with a small knurled end (also great to have). However, it sounds like your main issue is at 3/4 throttle and above, which would be the main.

Most of the reading I have done for a Stock TT250 at lower altitude puts the main jet size at a 110, needle in the 4th slot, and 1 1/2-1 3/4 out on the idle mixture screw,

If it were me, I would just order a 108 and 110 from JetsRus and call it a day. They are really fast with their shipping, usually only takes 2 or 3 days to arrive.