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frankresso
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|  | valve adjustment
« Thread Started on Apr 28, 2010, 9:37pm » | |
hello i have a roketa mp250a jcl. it did not run when i got it , cleaned evrything. did a valve adjustment will run now ( set the intake at .011 and the exhaust at .018) spuders when you throttle it or if to fast will stall. are these the right setting? any help would be great thanks guy's
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fubar05
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| | Re: valve adjustment
« Reply #1 on Apr 28, 2010, 9:44pm » | |
are you using a mm feeler or inch?
i am waiting for the corect settings in the vacume pump intermitent thread .
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widehide
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| | Re: valve adjustment
« Reply #2 on Apr 28, 2010, 10:00pm » | |
Set the intake to .004 +/- .001 and set the Exhaust to .006 +/-.001, These are english not Metric measurements.
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Both Scooters are running good , 4200 miles on Roketa 54B, 5400 miles on VOG 260. Only minor problems so far |
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fubar05
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| | Re: valve adjustment
« Reply #3 on Apr 28, 2010, 10:04pm » | |
ty so much !
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frankresso
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| | Re: valve adjustment
« Reply #4 on Apr 28, 2010, 10:56pm » | |
would not run when was that close widehide. have seen that video on youtube that i am sure most of us seen. so it should be .004 for the intake not .010 to .012 and .006 for the exhaust not .018? mine was set to that and would not run. i bought this not running. got it to run but slugish from a start. pleas respond widehide and thanks. any one with ideas can help me. and there is a new plug in it aswell if i could call someone pm me thanks
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dabucs
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| | Re: valve adjustment
« Reply #5 on Apr 29, 2010, 8:24am » | |
I have mine set to .004 on the intake and I did .005 on the exhaust, and it works fine 
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Bluefront
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| | Re: valve adjustment
« Reply #6 on Apr 29, 2010, 8:56am » | |
I don't like the noise with the valves set at .005".....my manual gives a setting of about .002".
After I did a BBK on my 50 GY6, I set both valves at a snug .003. No problems so far. Actually....the wider you set the clearance, the less mixture is getting into the combustion chamber (less power).
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frankresso
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| | Re: valve adjustment
« Reply #7 on Apr 29, 2010, 9:53am » | |
ok will try
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007
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| | Re: valve adjustment
« Reply #8 on Apr 29, 2010, 10:37am » | |
Linhai 257cc will not run properly at all at those settings.
Has to be set at .004 on intake, .005 on exhaust, does not clatter at .005. Totally different machine than 50cc, totally different engine, yamaha/linhai clone.
Exhaust valve too close will result in poor vacuum and pump not working right, hard start. stall at every stop sign, poor power, bad gas mileage.
totally different than Gy-6 and Cf Moto.
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Bluefront
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| | Re: valve adjustment
« Reply #9 on Apr 29, 2010, 1:08pm » | |
^^^^^The point is that you should be able to use the settings in the service manual for your model. You do need to determine if the setting is listed in mm or inches.....can be confusing.
So you're saying this 250 won't run properly at .003" clearance....but will run at .005"? Don't really buy that.....
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007
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| | Re: valve adjustment
« Reply #10 on Apr 29, 2010, 2:47pm » | |
Have you ever set the valves and rode a linahi clone? Totally different aspects of the way the engine is. The tighter the valves especially the exhaust the poorer it runs and the manual they send with this scooter has no settings in it. It's very vague. After the scooter breaks in somewhat it will run at .003 fairly well but as the exhaust valve closes it starts the classic signs of poor starting, stalling, loss of power etc.
Most of the time first valve setting is at around 1000 miles, and then it's play it by ear. Again this is the horizontal linahi not the vertical Cf Moto.
What you might buy and what is fact may be two different things and my advice was from a mechanic that owns one and there are others here that can tell you this engine performs somewhat differently than most.
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Bluefront
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| | Re: valve adjustment
« Reply #11 on Apr 29, 2010, 4:19pm » | |
I'm still not following you here.....obviously if the valve tightens up to zero clearance, you're going to have problems. But that could happen with an initial setting of .003 or .005.
If you're having the valves tighten up all the time, you have a problem other than the initial setting. By setting the valves at .005, they won't tighten up to zero clearance as fast as if you had set the valves at .003.....but that still doesn't fix the tightening up issue.
Is this model engine known for excessive valve or valve seat wear?
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007
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| | Re: valve adjustment
« Reply #12 on Apr 29, 2010, 5:52pm » | |
It's known for it's tight tolerances and being picky on the valve settings. The only way to really know is to ride one yourself. Experienced people who own this engine can tell quickly when the valves are starting to close up, may still run well but running great is a different thing.
Ones who own and have driven a scooter with the engine can testify to the fact that when the valves are correct not just close the difference between the two.
It does not follow the theory of the hand grenade "close enough".
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tomcas
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| | Re: valve adjustment
« Reply #13 on Apr 29, 2010, 6:56pm » | |
Apr 29, 2010, 1:08pm, Bluefront wrote:^^^^^The point is that you should be able to use the settings in the service manual for your model. You do need to determine if the setting is listed in mm or inches.....can be confusing.
So you're saying this 250 won't run properly at .003" clearance....but will run at .005"? Don't really buy that.....
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I agree 100%. If you set the valves correctly and the bike is otherwise OK then it won't make any difference between .003 and .005.
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tomcas
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| | Re: valve adjustment
« Reply #14 on Apr 29, 2010, 7:00pm » | |
Apr 28, 2010, 10:56pm, frankresso wrote:| would not run when was that close widehide. have seen that video on youtube that i am sure most of us seen. so it should be .004 for the intake not .010 to .012 and .006 for the exhaust not .018? mine was set to that and would not run. i bought this not running. got it to run but slugish from a start. pleas respond widehide and thanks. any one with ideas can help me. and there is a new plug in it aswell if i could call someone pm me thanks |
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Then you are either setting them wrong or something else is wrong with the engine.
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dabucs
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| | Re: valve adjustment
« Reply #15 on Apr 29, 2010, 7:40pm » | |
I have no clatter in my valves using .004 for intake and .005 for exhaust...when i first did the adjustment i had clatter like crazy, but that was because i was turning the stem as i was tightening it down...i ended up buying a valve adjust tool and when i set the valves using that tool to hold the stem down. She purred like a kitten...i did that adjustment at around 1k miles and I have over 2400 miles on the bike now...no stalling or hard starting issues for me
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007
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| | Re: valve adjustment
« Reply #16 on Apr 29, 2010, 10:06pm » | |
Apr 29, 2010, 6:56pm, tomcas wrote:
Apr 29, 2010, 1:08pm, Bluefront wrote:^^^^^The point is that you should be able to use the settings in the service manual for your model. You do need to determine if the setting is listed in mm or inches.....can be confusing.
So you're saying this 250 won't run properly at .003" clearance....but will run at .005"? Don't really buy that.....
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I agree 100%. If you set the valves correctly and the bike is otherwise OK then it won't make any difference between .003 and .005. |
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Then you agree with the close enough theory too? Will also ask you the question, have you rode or adjusted a linhai 257cc? If not then what are you basing your opinion on?
If .002 doesn't make any difference then why does the Gy-6 clack at .006 but run quite at .004?
I'm basin my opinion on the fact of owning and riding one and knowing how they act with poorly adjusted valves.
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frankresso
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| | Re: valve adjustment
« Reply #17 on Apr 30, 2010, 2:58am » | |
WOW thanks for all the info. hey anything will run better than what i set them at (except set at zero) hey it run at the setting i set them at so i just to make better way too open at (intake at .011 and exhuast at .018) what a tapping noise there and wont take off the greastest. this bike has 1947 miles on it. think i will be good to go. going to cut threw the battery box, so i don't have to take the top (plastic offand storage compartment to) this will save hours lol thanks
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tomcas
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| | Re: valve adjustment
« Reply #18 on Apr 30, 2010, 10:06am » | |
Apr 29, 2010, 10:06pm, 007 wrote:
Apr 29, 2010, 6:56pm, tomcas wrote:
I agree 100%. If you set the valves correctly and the bike is otherwise OK then it won't make any difference between .003 and .005. |
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Then you agree with the close enough theory too? Will also ask you the question, have you rode or adjusted a linhai 257cc? If not then what are you basing your opinion on?
If .002 doesn't make any difference then why does the Gy-6 clack at .006 but run quite at .004?
I'm basin my opinion on the fact of owning and riding one and knowing how they act with poorly adjusted valves. |
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I'm not saying it won't clack, I'm saying the performance difference is negligible.
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007
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| | Re: valve adjustment
« Reply #19 on Apr 30, 2010, 8:22pm » | |
How do you know? Again have you ever worked on or rode the 250A with the linhai? In fact it's also a known fact that in cold weather the valve adjustment being too tight will cause this particular engine to be extremely difficult to start. So if .005 and even some go to .006 when it's cold will make it start better than at .003 I would say it is negligible?
If you knew this engine then you would not make this statement. So to me it seems that you are just guessing or basing your opinion on no fact of working with or dealing with this engine?
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frankresso
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| | Re: valve adjustment
« Reply #20 on Apr 30, 2010, 8:51pm » | |
i concur that to close wont start lol, to far starts get no get up out of the hole  i think james bond wins
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tomcas
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| | Re: valve adjustment
« Reply #21 on Apr 30, 2010, 9:32pm » | |
Apr 30, 2010, 8:22pm, 007 wrote:How do you know? Again have you ever worked on or rode the 250A with the linhai? In fact it's also a known fact that in cold weather the valve adjustment being too tight will cause this particular engine to be extremely difficult to start. So if .005 and even some go to .006 when it's cold will make it start better than at .003 I would say it is negligible?
If you knew this engine then you would not make this statement. So to me it seems that you are just guessing or basing your opinion on no fact of working with or dealing with this engine? |
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I never adjusted the valves on this engine but have adjusted a crap load of other scooter and motorcycle engines.
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widehide
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| | Re: valve adjustment
« Reply #22 on Apr 30, 2010, 10:30pm » | |
This all sounds real cool and very enlightening however, Both my 257cc (54B and VOG260) engine scooters are set to .004 inch intake and .006 inch exhaust as close as I can get them. Both have about 4K miles. The 54B Roketa has required adjustment 2 times, The Vog260 has never needed adjustment. There is no clatter on either. The 2 engines are from different factories with different Carburetors and Clutch size. So it is possible we can't really say one setting is good for all. Normally set to .004-.005 intake, .005-.006 inch exhaust , If you get this close you are OK.
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Both Scooters are running good , 4200 miles on Roketa 54B, 5400 miles on VOG 260. Only minor problems so far |
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NDscootness
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| | Re: valve adjustment
« Reply #23 on Apr 30, 2010, 10:43pm » | |
So...I was suppose to do a valve adjustment last week when I had all of the plastics off, but I didn't, so I was wondering...
I know what you are suppose to set them cold on the 257(which I have), but...I was reading that with the CFMoto that you can set them while it is hot...is there any way of doing this with the 257? Can I pull the covers off, warm it up, and then set the clearance?
I've got 1200 miles on my MC-250A, and I think it is time, I'm just wondering if anyone thinks that it would work to set the clearance on a warm engine.
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cruiser66
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| | Re: valve adjustment
« Reply #24 on Apr 30, 2010, 11:00pm » | |
Setting the valve clearance on a warm or hot engine involves having the engine running. The CfMoto engine adjustments are made without removing any covers - the adjusters are on the outside of the valve cover. In order to do a valve adjust on the Linhai, you have to remove the valve covers. Running the engine this way would be very messy especially doing the exhaust valve. In order to do an accurate valve adjust on a warm engine, it has to be running. The spec for the valve gaps would also be different for hot or warm versus cold. The CfMoto engine does not use feeler gages for valve adjustments which also enhances the valve adjust on this engine.
66
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007
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| | Re: valve adjustment
« Reply #25 on Apr 30, 2010, 11:10pm » | |
http://scootdawg.proboards.com/index.cgi....ay&thread=21566
One has to adjust this engine cold and like Cruiser66 said the valve adjustment on the Cf Moto is entirely different. As you can see in this pictorial this engine has to be lined up on two timing marks also and don't make the mistake of having it 180 degrees off.
Quote:| I've got 1200 miles on my MC-250A, and I think it is time |
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Yes it's almost time and the classic signs are poor idling, stalls at stops, hard starts, and loss of power.
Quote:| I never adjusted the valves on this engine but have adjusted a crap load of other scooter and motorcycle engines |
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Then your opinion on how the valves need to be set is based on what you have done to other scooters and such and not on this engine.
I have adjusted the valves on lots of other engines too and also this one so again I speak of what I know not what I might think.
Besides if one is going to take the time to go to all the trouble to open it up and adjust them why not do it correctly instead of just close enough?
The linhai is a great engine but also like Cruiser 66 said one of the benefits of the 244cc CF Moto clone is the valve adjustment, easier, faster and on the ones I've worked on a lot less.
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widehide
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| | Re: valve adjustment
« Reply #26 on Apr 30, 2010, 11:12pm » | |
cruiser66, right on, that about settles the valve adjust process, thanks, here is a bone.
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Both Scooters are running good , 4200 miles on Roketa 54B, 5400 miles on VOG 260. Only minor problems so far |
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cruiser66
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| | Re: valve adjustment
« Reply #27 on Apr 30, 2010, 11:15pm » | |
Thanks for the treat, wide.
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frankresso
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| | Re: valve adjustment
« Reply #28 on May 2, 2010, 11:10am » | |
di the valves last nite. set them at .004 for intake and a tight .006 for the exhuast fors fine. THANKS TO ALL OF YOU!!!!!!!! got to adjuste the crab and fulsh the coolant out of it. thanks again guys
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