MT350

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Para1
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MT350

Post by Para1 » Fri Jun 21, 2019 4:04 pm

I vaguely remember the cold starts in my past, but are there any new solutions to getting it to tickover on cold start on the 350?
Read the thread on the 500 and the new carb, but wondered if anybody has found a solution to it on the 350.
Just had a full service from a dealer who owned one and he had the same issues.
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Force Motorcycles
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Re: MT350

Post by Force Motorcycles » Fri Jun 21, 2019 5:04 pm

Hi,

Having had hundreds of these through our hands over the years, I think the people you've spoken to have got it right.

When started from cold I think they need full choke. But, like a lot of other bikes, they will quickly start to bog down if you don't hover around them knocking some choke off constantly.

A properly set-up bike (especially this time of year) is soon off choke anyway, and I would expect it to be able to run with no choke at all after 45 seconds or a minute.

This probably doesn't entirely answer your question, but we have never really come across one of these bikes that was entirely happy until off-choke.

Regards,

Force
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sparky
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Re: MT350

Post by sparky » Fri Jun 21, 2019 5:06 pm

Fit a 42 slow jet. Mine ticks over lovely from cold and I can almost ride it immediately. My enrichener (choke) is off within a mile and the plug is a good colour - a mid to light brown. I've done all the carb mods but I still have the standard filter at the moment. I'll fit a free-flowing K&N type when I see one.
Dave.
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1994 MT350
1960 AJS model 20
1960 Matchless 650 CSR
1999 BMW F650ST
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MTBrown
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Re: MT350

Post by MTBrown » Fri Jun 21, 2019 6:04 pm

On all of my MT350's and MT500's, I find the choke/enricher is needed just to fire up the motor and then has to be switched off a matter of a few seconds later. I'm sure this is a limitation of an enricher device, whereas, old fashioned AMAL carbs with proper choke valves (or slides) allow you to reduce the amount of mixture enrichment more gradually and make it easier to warm up the motor.
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Wirralman
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Re: MT350

Post by Wirralman » Fri Jun 21, 2019 8:00 pm

Solutions , you ask

1) Clean the tank out internally, ideally treat it to POR 15
2) Strip and clean fuel tap
3) Discard anti-tilt valve if it is still there
4) fit an in-line fuel filter
5) Un-hock enriched cable at the handlebar end
6) Detach throttle cables
7) Remove carb from bike
8) Strip and clean the enrichener circuit ( vitual to make sure fine drilling is clean, poke thin wire through), remove jets and clean ( to remove main jet turn it fully in and note how many turns) Some people say ultrasonic is the only way but manual cleaning is quite effective
9) Fit 42 pilot as mentioned
10) check main diaphram, no holes, flexible but not floppy
11) check that main spring is not worn ( ie sides are flattened off not round)
12) check accelerator pump diaphram is flexible with no holes/years
13) clean float bowl
14) search forum or Harley sites about enlarging a hole to allow slide to be more responsive
15 ) If you are tempted to raise the main needle with washers , it may or may not work Personally I never bothered messing about with washers but some do
16) Some people say that you should cut holes in the airbox, many have done this then regretted it ( lots of noise but no actual difference in performance

When it's all back together, run the engine up to normal working temperature the adjust main jet setting ( around 2 turns out is a good place to start) for optimal performance

The military manuals say ride off as soon as the engine starts , don't let it warm up by idling ( try it by all means but don't be surprised if it dies and subsequently hard to start)

I found that warm up time on 40 pilot was in total 5 miles and with 42 pilot, 3 miles, turning the enrichener off progressively after a couple of miles

Try to turn the enrichener off too soon and it dies , leave it too long and it chokes. I ran two MT350 one with a 40 and one with a 42- apart from the warm up length they both had the same performance topping out at an indicated 74mph ( ish) regardless of weight of luggage With to original T63 that is, if you fit Distanzias or the type that replaced it, a few mph more but engine screaming

If you need a bike that runs clean from cold, buy a modern bike with electrically controlled injection If you want a bike with character stick with the MT
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sparky
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Re: MT350

Post by sparky » Sat Jun 22, 2019 11:22 am

Eric, you mean the mixture screw which is accessed by carefully drilling out the soft plug. It has a very fine point and you need to be carefull not to loose the spring, washer and 'O' ring if you remove it for cleaning out. The main jet is a removeable but not adjustable, you would need to change for another size.
I think if it's been serviced and just won't idle when cold just changing to a 42 slow jet would do it. (If it ain't broke don't fix it!)
Dave.
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1994 MT350
1960 AJS model 20
1960 Matchless 650 CSR
1999 BMW F650ST
Honda XBR500

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hounddog
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Re: MT350

Post by hounddog » Sat Jun 22, 2019 12:34 pm

One very commonplace solution is a carb modification to the standard HD carb. It was factory set to comply with Californian emission regulations ( as I understand) which does restrict the power output , and the mixture screw is blanked off. The modification is a DIY job and we have a tutorial on how to do it , not difficult for anyone with normal servicing skills . Totally transformed my bike when de restricted , faster , more power and warms up better. A modified carb should take a 350 off the 70mph clock ok.
Even now it can take a couple of miles to get the oil warmed up etc and idling smooth especially in cold weather , so don't expect perfection immediately from cold .

Some owners have swapped the carb for a dellorto or mikuni with good results ,but I find the Keihin HD one good enough for what I need , depends on budget and how fast you want to go to some degree
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Wirralman
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Re: MT350

Post by Wirralman » Sun Jun 23, 2019 11:46 pm

sparky wrote: ↑
Sat Jun 22, 2019 11:22 am
Eric, you mean the mixture screw which is accessed by carefully drilling out the soft plug. It has a very fine point and you need to be carefull not to loose the spring, washer and 'O' ring if you remove it for cleaning out. The main jet is a removeable but not adjustable, you would need to change for another size.
I think if it's been serviced and just won't idle when cold just changing to a 42 slow jet would do it. (If it ain't broke don't fix it!)
Dave.
'Carefully drilling out' , merely piercing the soft plug with a sharp tool is quite sufficient
The enrichener circuit is only in operation during start up and initial warm up period allowing additional fuel to create a rich mixture.

If the bike is new to you , my philosophy is trust no-one and check / service yourself .

I bought one MT350 which came with 6 servicing receipts, the last one included a new front tyre. As I could lose nothing and had seen another owners tyre deflate due to a perished tube, I removed the new tyre and found a very tired looking inner tube and an old rim tape which had been heavily patched with gaffa tape. For me , I had to put in a new tube , rim tape and new wheel bearings whilst I had the wheel off.

' Failing to prepare is Preparing to fail' is a good maxim to follow. I fully accept the 'ain't broke' point but in my book it a bike isn't working properly you either live with the fault or you fix it.

I have been in the company of more than one MT owner whose bike has failed due to lack of care. When riding old bikes that may have had a hard life , it comes down to the Dirty Harry question ' You feeling lucky?'...servicing improves your luck

That said I fully agree with the point about being careful. Hopefully, a rider's own self-interest would encourage him/her to take care but have heard of bodged MT ' 'improvements' leading to the need for a recovery truck

The other point is that new owners who are used to the good manners of a modern bike may be expecting an old style MT to behave in the same manner
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Minter
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Re: MT350

Post by Minter » Mon Jun 24, 2019 6:39 am

We at Sportax recommend the 42 pilot jet and removing the anti tamper plug. The mixture screw should then be screwed all the way in then out 2 and a half turns. We carry this out as well as other carb improvements on all the MT350's we get in for servicing and maintenance with great feedback from the owners.

The other solution is it to fit one of our dellorto performance carbs set up to work perfectly with the MT350.
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Para1
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Re: MT350

Post by Para1 » Sat Nov 02, 2019 7:39 am

Thanks guys very helful I'll let you know how I get on............... :D
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