Go Back   ChinaRiders Forums > Technical/Performance > Dual Sport/Enduro
Register FAQ Community Calendar Today's Posts Search
Reply
 
Thread Tools Search this Thread Display Modes
Old 04-25-2022, 08:56 AM   #1
Thumper   Thumper is online now
 
Thumper's Avatar
 
Join Date: Feb 2021
Location: Kansas City
Posts: 2,265
Slide height screw (idle)

This is a photo of the slide height adjustment screw (idle) on a new TBR7. We rejet it (both jets) and shimmed the needle. It starts right up, runs great, and no popping. But the idle adjustment seems too short! There is no spring on it, and it is all the way in. It has no effect on the slide height!

This might be normal for this carburetor, but how do you adjust the idle?

Name:  IdleAdjust.JPG
Views: 262
Size:  136.6 KB



Last edited by Thumper; 04-25-2022 at 10:05 AM.
 
Reply With Quote
Old 04-25-2022, 03:56 PM   #2
buzz   buzz is offline
 
Join Date: Dec 2020
Location: Dayton Pa.
Posts: 861
Thats the idle screw works on mine.


 
Reply With Quote
Old 04-25-2022, 05:30 PM   #3
Megadan   Megadan is offline
 
Megadan's Avatar
 
Join Date: Apr 2017
Location: Omaha, NE
Posts: 7,990
Suggestion. The part that acts on the slide is just an offset pin on the screw. Back it out until the slide ends up at the same place, that will give you more room for adjustment.
__________________
Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331
2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1
2024 Royal Enfield Shotgun 650
https://chinariders.net/showthread.php?t=34124


 
Reply With Quote
Old 04-25-2022, 05:53 PM   #4
Bruces   Bruces is online now
 
Join Date: May 2018
Posts: 1,577
Any chance your throttle cable is adjusted too short ?


 
Reply With Quote
Old 04-25-2022, 06:58 PM   #5
Thumper   Thumper is online now
 
Thumper's Avatar
 
Join Date: Feb 2021
Location: Kansas City
Posts: 2,265
Oh, I see

Thanks, all of you. Why didn't I try removing it? It was always all the way in. Yes, there is indeed a spring on it.

Mega, I don't quite understand what you are saying. If the screw is all the way in, the slide is held at highest point the pin can hold, right? How can unscrewing it do anything except drop the slide? The pin is fixed length (one solid piece of brass). Thing is that it doesn't seem to change the slide height.

Name:  SlideHeightScrew.JPG
Views: 250
Size:  188.9 KB


 
Reply With Quote
Old 04-25-2022, 07:04 PM   #6
Thumper   Thumper is online now
 
Thumper's Avatar
 
Join Date: Feb 2021
Location: Kansas City
Posts: 2,265
Quote:
Originally Posted by Bruces View Post
Any chance your throttle cable is adjusted too short ?
Thanks... I just checked and in fact there is about 1/3 inch slack before the cable even moves the slide! Removing the adjustment screw did not change that, so the slide appears to be bottomed out WITH or WITHOUT the adjustment screw all the way in!

I need to pull the slide and verify that the place where the pin engages is not damaged. The pin does not seem to do anything to slide height.

I think MegaDan is implying that the screw all the way tightened has not adjustment in that position, which is true! But the idle is NOT elevated at all. On my "Youall" PZ30 carb, I can set the slide height screw to 1500rpm idle! Maybe more. I always twist the throttle when I screw it in, so it isn't grinding the beveled surface it pushes. Then I let it go and back off the screw to desired setting.


 
Reply With Quote
Old 04-25-2022, 09:12 PM   #7
Megadan   Megadan is offline
 
Megadan's Avatar
 
Join Date: Apr 2017
Location: Omaha, NE
Posts: 7,990
Quote:
Originally Posted by Thumper View Post

Mega, I don't quite understand what you are saying. If the screw is all the way in, the slide is held at highest point the pin can hold, right? How can unscrewing it do anything except drop the slide? The pin is fixed length (one solid piece of brass). Thing is that it doesn't seem to change the slide height.

Attachment 26774
The slide is raised and lowered by the pin. There are two types. one where the pin has an offset to it and is smaller in diameter than the threads. This means its acts like a cam on the slide, manually raising and lowering it. The other type, which is what appears to be your style, is just a rounded end that "ramps" the slide up and down. Move it in and it lifts the slide with the radius of the rounded end, move it out and it lowers it. With it being screwed all the way in, it's just riding the slide as high as it can go all the time.

In either instance, backing it out still resolves the issue. For the first type I mentioned, since the screw was bottomed out and not allowing for any adjustment, it would move the offset pin back in place, but with a full rotation or two to work with, thus giving it full up and down movement. In the latter, as you discovered with yours, it puts it on the end of the pins rounded edge, putting you back into the area where it actually can affect the slide position and change the idle speed.
__________________
Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331
2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1
2024 Royal Enfield Shotgun 650
https://chinariders.net/showthread.php?t=34124


 
Reply With Quote
Old 04-26-2022, 08:35 AM   #8
Thumper   Thumper is online now
 
Thumper's Avatar
 
Join Date: Feb 2021
Location: Kansas City
Posts: 2,265
Quote:
Originally Posted by Megadan View Post
The slide is raised and lowered by the pin. There are two types. one where the pin has an offset to it and is smaller in diameter than the threads. This means its acts like a cam on the slide, manually raising and lowering it. The other type, which is what appears to be your style, is just a rounded end that "ramps" the slide up and down. Move it in and it lifts the slide with the radius of the rounded end, move it out and it lowers it. With it being screwed all the way in, it's just riding the slide as high as it can go all the time.

...
Your description matches my assumption on how it works. Yes, all the way tight should adjust the slide to highest adjustment/position possible-highest idle speed. But the thing is, the idle is like 700-800rpm, not elevated at all! It doesn't seem to lift the slide. It is freezing cold in the garage this morning. I will take another look this afternoon when it is at least in the 50s!

By contrast, on my storm, I can set the idle to practically 2000 rpm with this slide position adjuster.


 
Reply With Quote
Old 04-26-2022, 08:49 AM   #9
JerryHawk250   JerryHawk250 is online now
Moderator
 
JerryHawk250's Avatar
 
Join Date: Oct 2016
Location: Houma, La.
Posts: 11,554
Open the throttle a little before turning that screw in. It might be hitting the side of the slide instead of lifting the slide.
__________________
2023 Lifan Lycan 250 Chopper
2023 Venom Evader
2022 Lifan KPX250
2020 Kawasaki Vulcan S
2004 Honda ST 1300
2016 Black Hawk 250 (sold)
Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster
2016 Cazador180 XL
2014 Coolster150
JerryHawk250.com
My YouTube Channel


 
Reply With Quote
Old 04-26-2022, 09:05 AM   #10
Thumper   Thumper is online now
 
Thumper's Avatar
 
Join Date: Feb 2021
Location: Kansas City
Posts: 2,265
I always twist the throttle a bit and hold it when I tighten the screw (as you suggest), because I don't want it to damaged the slide. Then I drop it back down (unscrew it) to make a final adjustment. I just wonder if it was already damaged when we got the bike.

It is a knurled head on the Storm, so I can easily adjust it anytime. I might file some ridges in this one so it can be easily turned by hand.

this TBR7 has only about 1 mile on it, just up and down the street test drive. We did change the oil, rejet (both jets), shimmed the needle ~1mm, and adjust the valves before starting it. And it starts right up.


 
Reply With Quote
Old 04-26-2022, 11:06 AM   #11
Thumper   Thumper is online now
 
Thumper's Avatar
 
Join Date: Feb 2021
Location: Kansas City
Posts: 2,265
I rolled it out and fired it up. The idle screw has no effect when it is cold, no matter what the choke position is. It just doesn't lift the slide far enough.

After it warms up, it works but can only elevate the idle to about 1000 rpm. I think it needs to be a mm or 2 longer to be useful.

I use that adjustment on my Storm all the time when it is cold. It can lift the slide a lot more, I guess.


 
Reply With Quote
Old 04-26-2022, 11:13 AM   #12
JerryHawk250   JerryHawk250 is online now
Moderator
 
JerryHawk250's Avatar
 
Join Date: Oct 2016
Location: Houma, La.
Posts: 11,554
Did you try it without the spring just to see if it will work? You might be able to trim the spring if it does to allow more adjustment turning it in.
__________________
2023 Lifan Lycan 250 Chopper
2023 Venom Evader
2022 Lifan KPX250
2020 Kawasaki Vulcan S
2004 Honda ST 1300
2016 Black Hawk 250 (sold)
Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster
2016 Cazador180 XL
2014 Coolster150
JerryHawk250.com
My YouTube Channel


 
Reply With Quote
Old 04-26-2022, 12:15 PM   #13
Thumper   Thumper is online now
 
Thumper's Avatar
 
Join Date: Feb 2021
Location: Kansas City
Posts: 2,265
Quote:
Originally Posted by JerryHawk250 View Post
Did you try it without the spring just to see if it will work? You might be able to trim the spring if it does to allow more adjustment turning it in.
The adjustment screw can be tightened all the way (as it is in the first photo above) with the spring in place, so it can't be any farther in, even without the spring.
Maybe the bevel on the slide that the pin sits on is not in the right position for this carb. A longer adjustment screw might be the answer.

This may be an example of mismatched generic parts that we see so often on these bikes, like my kick started on the storm that bruised my calf!

At least it works marginally once warm. We can live with it for now.


 
Reply With Quote
Old 04-26-2022, 12:57 PM   #14
JerryHawk250   JerryHawk250 is online now
Moderator
 
JerryHawk250's Avatar
 
Join Date: Oct 2016
Location: Houma, La.
Posts: 11,554
Quote:
Originally Posted by Thumper View Post
The adjustment screw can be tightened all the way (as it is in the first photo above) with the spring in place, so it can't be any farther in, even without the spring.
Maybe the bevel on the slide that the pin sits on is not in the right position for this carb. A longer adjustment screw might be the answer.

This may be an example of mismatched generic parts that we see so often on these bikes, like my kick started on the storm that bruised my calf!

At least it works marginally once warm. We can live with it for now.
Oh, I see what you are talking about now. I just noticed the screw head was hitting. Try filing or grinding down the case some so it can go in farther. At this point it would hurt to try.
__________________
2023 Lifan Lycan 250 Chopper
2023 Venom Evader
2022 Lifan KPX250
2020 Kawasaki Vulcan S
2004 Honda ST 1300
2016 Black Hawk 250 (sold)
Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster
2016 Cazador180 XL
2014 Coolster150
JerryHawk250.com
My YouTube Channel


 
Reply With Quote
Old 04-26-2022, 03:15 PM   #15
Thumper   Thumper is online now
 
Thumper's Avatar
 
Join Date: Feb 2021
Location: Kansas City
Posts: 2,265
Quote:
Originally Posted by JerryHawk250 View Post
Oh, I see what you are talking about now. I just noticed the screw head was hitting. Try filing or grinding down the case some so it can go in farther. At this point it would hurt to try.
A replacement carb cost under $40, and I think I can shave a mm or 2 off the body without destroying it. That would allow the screw to get deeper.

It is not that bad, and actually fine once warmed up, but I may try it. Good idea.


 
Reply With Quote
Reply



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 03:03 PM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.