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Post by crispin on May 1, 2017 18:04:36 GMT
Hi all
I have a standard t5 mk1 with a sip road race 2 exhaust
Problem is I have a 115 main jet fitted but it bogs bad when you rev the engine.
And to get it to run ok the mixture screw is 6 turns out :-(
Seen so many conflicting posts as usual lol
Thinking of putting in a 122 main jet. ?
And would it be better if I drill the filter with a 5mm and 7mm holes
Thanks
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Post by crispin on May 2, 2017 19:05:03 GMT
Anyone ?
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Post by henri on May 6, 2017 9:34:28 GMT
a t5 filter is already drilled if its standard ,24/24g carb ,ya cant get new original filters only sip ones .my stock t5 an mates 1 both on sip road pipes run a 116 on his an a 118 on mine .my polini 152 t5 runs a 122 so reckon that might be a tad large for yours .
maybe theres something else going on ,as main jet size wont effect mixture screw setting ,an at 6 turns out it should be very smokey/rich . i'd check my timing an remove/strip/clean an re-torque your carb with new gaskets ,under carb box too . H
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Post by crispin on May 6, 2017 14:44:59 GMT
Will strip and clean carb later and put 115 jet in.
And see if that helps
Thanks for your help
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Post by crispin on May 6, 2017 18:01:05 GMT
Stripped the carb put in ultrasonic cleaner and blown out with air compressor.
Put back on with 115 main jet as that's the biggest I have below 120.
Ordering some between 110 and 120 so have full set.
Been out and rides ok but a bit rough low down but mixture screw is out 5 to 6 turns still ?
Got autolube on and 2% mix still in the tank as just rebuilt scooter and had to wait for auto lube to work
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Post by pxguru on May 7, 2017 4:48:39 GMT
Why is the mixture screw out so far? Any more than 3 whole turns indicates that there is some issue, somewhere. The mixture screw does only affect tickover and just opened throttle, so rough low down is something else.
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Post by crispin on May 7, 2017 9:47:01 GMT
Its bogs on pull off and ok after that.
Air filter is not drilled and has heart shape still in.
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Post by pxguru on May 7, 2017 10:12:23 GMT
Maybe the air filter is not a T5 one! I thought all the T5 ones were drilled from the factory.
Bogging on pull off might be flooding on pull off. Try the mixture screw wound nearly right in (in is weaker) and see what happens
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Post by crispin on May 7, 2017 11:30:58 GMT
Screwed right in
Or just out it cuts out.
Just checked air filter had 3mm hole drilled over main jet.
Drilled it to 7mm and drill other to 5mm as show on a post.
Still runs with screw right out :-(
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Post by pxguru on May 7, 2017 12:44:13 GMT
Have you checked your pilot jet is clear? There is tiny hole right in the end of the jet that often gets blocked. Sometimes it will only clear by poking something through it
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Post by crispin on May 7, 2017 17:45:31 GMT
 Cleaned jets again Checked for air leaks Drilled air filter 7mm and 5mm Altered mixture screw and still to far out with 115 main jet
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Post by pxguru on May 8, 2017 3:23:34 GMT
Seems like you are having too much trouble for a normal issue. They are just not that sensitive. I think you have an air leak somewhere and as ever when there is no other cause it is often the clutch oil seal. How is the gearbox oil level?
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Post by henri on May 8, 2017 16:29:27 GMT
the t5 filters comes with 1 hole over the main jet ,not measured mine but 3-4mm sounds right .as youve drilled that out to 7mm a larger mains needed ,around 118-120 is my guess . an a richer pilot jet aswell as youve drilled that too. H
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Post by crispin on May 8, 2017 18:59:03 GMT
Any idea what pilot jet size
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Post by crispin on May 9, 2017 17:51:11 GMT
Gearbox level ok and is a bit dark in colour.
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Post by pxguru on May 10, 2017 3:17:53 GMT
If the oil is nice, dark and similar thickness to how it went in, then unlikely to be a crankcase issue.
There is something making this weird though. It just isn't that difficult to set a mixture screw in the middle, to not bog when revved and still start when hot.
Compression would be then next thing to check.
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Post by crispin on May 10, 2017 19:20:18 GMT
Plug looks oily and wet
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Post by crispin on May 11, 2017 18:30:13 GMT
Update
Got a compression tester and its maxing out at 80 psi.
No air filter and on full throttle.
Took out carb put on glass sheet and it rocks ever so slightly.
So going to lap that so its level.
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Post by pxguru on May 12, 2017 4:02:07 GMT
Looks like you found your problem. 80 psi is terrible. Not good is less than 120 psi. Surprised it starts. You might get away with new piston rings. Or just get a 172 kit  |
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Post by henri on May 12, 2017 13:52:38 GMT
on a t5 its new rings every 3500 to 5000 miles , they eat em fast .at £30 a set its worth trying them 1st as 172 kits aint cheap . an i prefer the ridability of the 152's . H
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Post by crispin on May 12, 2017 17:15:55 GMT
16000 on the clock I don't know if they have ever been changed.
Do you just change them for a standard size ?
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Post by crispin on May 12, 2017 20:52:37 GMT
Removed head and there seems to be a bit of oil behind the piston is this normal or is it gear box oil. ?
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Post by henri on May 13, 2017 9:37:08 GMT
it will be 2 stroke oil most likely , an theres only one size of rings on a t5 . as its a nicasil bore there not re-borable just re-plateable,H
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Post by crispin on May 13, 2017 17:02:56 GMT
Some marks on the barrel you can just feel them with your nail. Is it best to upgrade to polini or molossi want it to be reliable and riding 2 up Hone and new rings ?  |
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Post by henri on May 14, 2017 6:20:49 GMT
ali/nicasil barrel ,cant be honed only re-plated ,langcourt in weston super mare bout £130 , plus a new piston an rings brings it up to £200 .not much more to buy a new kit .a new stock barrel an piston can be had for 175 or 2nd hand around the 100 mark .
if kitting a polini is nice with a sip road pipe ,the mazzi really needs a revy pipe to perform ,more expense .H
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Post by crispin on May 14, 2017 7:59:13 GMT
Are the marks to bad to reuse do you think ?
And if I buy the polini kit can I just use the standard head with no mods done to it.
Cheers
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Post by pxguru on May 14, 2017 11:03:37 GMT
Barrel doesn't look so bad. Only the scores above the exhaust port matter. If there is anything deep there then you might as well spend your money on a bigger barrel.
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Post by crispin on May 14, 2017 12:12:41 GMT
Marks at the cylinder top are smooth
Slight marks score marks that you can just feel at the bottom of the cylinder.
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Post by henri on May 14, 2017 14:42:16 GMT
as pxguru says , only marks above exhaust count , should be fine with new rings . the polini 152 can be used with a stock head ,the mazz 172 needs a head re-profiling to run right . H
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Post by crispin on May 14, 2017 15:58:04 GMT
Thanks for all your help ;-)
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Cleaned jets again