Upgrade or replacement Carb, MT350

For all that relates to both Armstrong MT 500 and Harley Davidson MT 350
Ricky
Posts: 21
Joined: Tue Oct 13, 2015 7:58 am
Location: lincolnshire

Upgrade or replacement Carb, MT350

Post by Ricky » Sat Nov 24, 2018 5:11 pm

Hi
I'm almost finished a full restoration of my MT350 , I have one major issue.

It passed its mot, however runs very badly and the Carb doesn't seem to want to stay set up. it ran quite well initially then I couldn't get it to start.

Very reluctantly I took it to a reputable bike repair place swallowing my pride and he doesn't seem to be able to get it to run correctly.

I know there are replacement Carbs but don't know where to source one from.

What are the replacement carbs called (who makes them) and where can i get one.?

How much are they ?

I know I can get a new old stock from LMS or Sportax but I thought I would give it a whirl on here first.

Many thanks for assistance , It's taken me 2.5 years to get to where I am with it due to work commitments and then changing jobs, I just want to get it out and ride it.

regards
Ricky
0 x

Wirralman
Posts: 4960
Joined: Fri Jan 16, 2009 9:45 am
Location: Wirral, Merseyside

Re: Upgrade or replacement Carb, MT350

Post by Wirralman » Sat Nov 24, 2018 6:20 pm

The carb is a CV Keihin
The usual problems are
-fine drilling to enrichener clogged making the bike hard to start and warm up (5 miles) . Fine wire gently poked through should clear it or ultrasonic cleaning
- diaphram split
-correct needle fitted ?
- jets clogged, easy to remove clean refit
- accelerator pump diaphram split
- fuel tap clogged
- fuel tank rusty

Have you tried running with your fuel cap unscrew a little, if the breather blocks you get a vacuum which reduces fuel flow

Have you opened the float bowl drain screw to flush out any old fuel

Have you removed the anti tilt valve in the fuel.line, they reportedly stick so most riders remove them and replace with an inline filter

Had your exhaust rusted internally preventing gas outflow. Is your air filter clean and dry( you can test run without it if needs be)

I will send you a pm
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Vtrsp1da
Posts: 419
Joined: Thu Jun 18, 2015 10:48 am
Location: Bisley
Location: Bisley

Re: Upgrade or replacement Carb, MT350

Post by Vtrsp1da » Sat Nov 24, 2018 6:42 pm

Sportax Racing do a Dellorto upgrade and Force motorcycles do a C V carb upgrade
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yeti341
Posts: 849
Joined: Fri Jun 19, 2015 9:29 am
Location: ammanford.wales

Re: Upgrade or replacement Carb, MT350

Post by yeti341 » Sat Nov 24, 2018 11:44 pm

Upgrade too a delorto from sportax you will be amazed at the difference
1 x

User avatar
Minter
Posts: 4455
Joined: Sun May 30, 2010 7:42 pm
Location: Burlington , Shropshire

Re: Upgrade or replacement Carb, MT350

Post by Minter » Sun Nov 25, 2018 2:38 pm

Hi Ricky,

Our Dellortos are brand new not old stock all available for next day delivery for 348, 405, 504, 555, 560, 604, 636, 676.

All tested on a dyno for optimum performance.


https://sportaxracing.co.uk/shop/dellor ... hf-34-kit/
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SPORTAX Racing ROTAX
http://www.sportaxracing.co.uk
MTRC Shopkeeper
http://sportaxracing.co.uk/product-category/mtrc-shop/
Manuals & Technical Publications on above MTRC shop link

appyarry
Posts: 1493
Joined: Wed Jan 12, 2011 9:39 pm
Location: Lyminge, Kent.

Re: Upgrade or replacement Carb, MT350

Post by appyarry » Tue Nov 27, 2018 10:17 am

Ricky wrote: ↑
Sat Nov 24, 2018 5:11 pm
I'm almost finished a full restoration of my MT350 , I have one major issue.
It passed its mot, however runs very badly and the Carb doesn't seem to want to stay set up. it ran quite well initially then I couldn't get it to start.
Personally I wouldn't be in such a rush to spend a lot on a new carb unless you are looking at improving the power above the standard issue.

The original carb is not bad CV's are pretty good for normal road work. Can you not borrow a known good one from somebody locally? Are you anywhere near Mr Shiney, he normally has a few renovated carbs that he may sell. The diaphragm is the normal thing that gets a hole (sometimes very small) or a split and that kills the performance. The rest of the carb is just jets and a pump that sprays petrol down the carb when you open the throttle quickly. So a rebuild kit is cheap and easily sourced, apart from the diaphragm they are a bit more expensive.

I'd make sure the carb is the problem before you spend loadsadosh only to find the problem is elsewhere.

Good Luck!
0 x
MT 604e :-)
Serveta Jet 200
Triumph Tigress 250
BSA C15 to be rebuilt as Scrambler
Sinclair Goddard PowerPak
Kalkhoff Endeavour 11 Speed Hub

deadgrass.
Posts: 890
Joined: Sun Jun 21, 2015 5:32 pm
Location: sheffield

Re: Upgrade or replacement Carb, MT350

Post by deadgrass. » Tue Nov 27, 2018 9:18 pm

Post by deadgrass » 15 Jan 2014 1944

i faffed about for ages with the cv carb, did the mods, altered jets [went to 65 slow 170 main], started ok top end ok, it was the lackluster way it got there it just spoilt the ride, so in the end i decided to see what more modern singles used, namely the drz400, the standard drz carb was the mikuni cv 36mm so i bought one and tried it, it was better but i had found out while doing my research on the drz that the holy grail carb for that bike was the 39mm keihin flat cr[fcr] so decided to look for one of these, only to find they are quite rare and quite pricey [also standard fit on drz s], while looking i also came across a 37mm fcr carb [2005 honda crf250] i thought the smaller carb might suit the 350 so bought one, with a bit of modding i got it to fit, i had to lower the needle to lowest setting for best results but the bike is now transformed starts well strong linear acceleration ,both my bikes will continue to accelerate past 70 uphill this is by far the best mod i've done to the 350.
dave.
1 x
born to be waserk
thank god for atheism.
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Gremlin
Posts: 52
Joined: Mon Mar 05, 2018 11:50 am
Location: Bristol

Re: Upgrade or replacement Carb, MT350

Post by Gremlin » Fri Nov 30, 2018 7:36 am

appyarry wrote: ↑
Tue Nov 27, 2018 10:17 am
Ricky wrote: ↑
Sat Nov 24, 2018 5:11 pm
I'm almost finished a full restoration of my MT350 , I have one major issue.
It passed its mot, however runs very badly and the Carb doesn't seem to want to stay set up. it ran quite well initially then I couldn't get it to start.
Personally I wouldn't be in such a rush to spend a lot on a new carb unless you are looking at improving the power above the standard issue.

The original carb is not bad CV's are pretty good for normal road work. Can you not borrow a known good one from somebody locally? Are you anywhere near Mr Shiney, he normally has a few renovated carbs that he may sell. The diaphragm is the normal thing that gets a hole (sometimes very small) or a split and that kills the performance. The rest of the carb is just jets and a pump that sprays petrol down the carb when you open the throttle quickly. So a rebuild kit is cheap and easily sourced, apart from the diaphragm they are a bit more expensive.

I'd make sure the carb is the problem before you spend loadsadosh only to find the problem is elsewhere.

Good Luck!
Mr Shiney!!!!!! I wouldn't buy feck all from that TW@
Everything he's sold to me in the past has been nothing but crap!
2 x

appyarry
Posts: 1493
Joined: Wed Jan 12, 2011 9:39 pm
Location: Lyminge, Kent.

Re: Upgrade or replacement Carb, MT350

Post by appyarry » Fri Nov 30, 2018 1:33 pm

Gremlin wrote: ↑
Fri Nov 30, 2018 7:36 am
Everything he's sold to me in the past has been nothing but crap!
I'm sorry to hear that, I've bought stuff from him over the years and not had a problem with any of it!

I know he's done plenty to help other members of this forum over the years. In fact IIRC he was Member of the year or similar a few years ago.

Thanks,
0 x
MT 604e :-)
Serveta Jet 200
Triumph Tigress 250
BSA C15 to be rebuilt as Scrambler
Sinclair Goddard PowerPak
Kalkhoff Endeavour 11 Speed Hub

Gremlin
Posts: 52
Joined: Mon Mar 05, 2018 11:50 am
Location: Bristol

Re: Upgrade or replacement Carb, MT350

Post by Gremlin » Fri Nov 30, 2018 3:57 pm

When we next meet, I can personally show you the results of his "help/expertise/services" many of us here can testify to the nature of his "help/services" and have the invoices sent by him to prove how much he values his expertise!!!! :o
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