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Post by twostroker on May 18, 2008 12:29:23 GMT 1
hi all,ive had my liner swapped for a 175cc jobbie with matching piston and head machined up to fit.(no head gasget just a o_ring and sealer for the water ways) any way its overheating and i was wondering if any body else has done the conversion and can help? i have changed the oil/water seal for the water pump,the water gets pumped round the system but only when over half throttle all i can think of is the original 125cc head gasget has a series of small holes for the water to flo through and now with no gasget its just open between the head and barrel  some one please help  |
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Post by pablo on May 18, 2008 16:52:12 GMT 1
hi all,ive had my liner swapped for a 175cc jobbie with matching piston and head machined up to fit.(no head gasget just a o_ring and sealer for the water ways) any way its overheating and i was wondering if any body else has done the conversion and can help? i have changed the oil/water seal for the water pump,the water gets pumped round the system but only when over half throttle all i can think of is the original 125cc head gasget has a series of small holes for the water to flo through and now with no gasget its just open between the head and barrel some one please help It sounds like those holes in the head gasket were there to build up pressure so the coolant would flow properly.A bit like the way water thru a hose-pipe speeds up when you pinch the end.I would say you need to sort out another form of restriction to get your coolant flowing properly again. |
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Post by twostroker on May 18, 2008 21:28:32 GMT 1
exactly wot i was thinking,but not wo i wanted to hear.looks like it may get a 125cc top end put back on.
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Post by twostroker on May 18, 2008 21:33:20 GMT 1
a bigger rad isnt realy an option if i can help it as i want it looking as standard as possable,norbo's the man to ask i suppose,should the water flow through when the engines on idol speed?
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Post by twostroker on May 19, 2008 21:04:33 GMT 1
ive just swapped the rad over for a another one thats like new inside,checked the pump is spinning up ok,and bled the system again it now runs at over half and just under 3/4 on the temp guage now,is this a safe running temperature?
has any body tryed that "water wetter" stuff that aparently makes engines run cooler?
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Post by mellow on May 19, 2008 22:49:58 GMT 1
"Water Wetter" can u get wetter than water then   |
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Post by twostroker on May 21, 2008 20:44:15 GMT 1
by sealer do you mean hylamar like instant gasket? have you gone overboard with it and blocked any of the coolant chambers a little? also the temp running at 1/2+ is this on tick over and not moving as when your running the air flow through the rad will drop this down? as will the impellor pumping the coolant round the system faster, dont mean to offend by saying this but take it for a spin n see if it drops any? just dont go mad cos you dont want it dropping a ring after all the time n effort you have put in on this mod.. trial n error mate me thinks.... if all else fails disconect the temp snder n its running cool hehe then jump on give it the berries n try n get some grin factor before it lets go lol ;D  ;D   as for the head gasket i dont think this is the issue as if memory serves its a pressurised system anyway? appols if im wrong it was over 8 years ago when i sold mine and at that point i was averaging 3 total rebuilds a year lol i used a thin smear of rtv sealer as advised by mr fahron. if sat running on idle it will be almost in redline in 5 minuites exactly the same if i ride it for 5 minuites it will also get to almost the red. i havent got a clue as to why?im going to try a copper gasget if i can find on and see how i get on i think. |
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Post by twostroker on May 24, 2008 8:11:43 GMT 1
ron supplied a matika piston kit and i trial fitted it to the bore before it went on the bike and id defenetly say the piston/ring is a perfect match for the bore size.i just want to get it sorted asap to enjoy the nice weather while i can,il let you know hou i get on with the copper gasget when i get it .
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Post by twostroker on Jun 28, 2008 17:17:36 GMT 1
i took it for a mot today,it passed with no advisariorys but its still running way too hot,all i can think of is the bigger liner has protruded into the water jacket too much thus it no longer has enough room for water to frow round the cylinder properly?
as the complete cooling system is a1 and has been bled countless times its got to be the barrel at fault,ive been debating wheather to take the barrel off again and file the water ways out my self or should i send it off to be done properly?
i would just convert it back to 124cc but i havent got any parts to do it so it would cost alot more then sorting the 175cc barrel,as it runs so hot i wouldnt be surprised if when the barrel is removed my brand new liner/rings isnt looking as pretty as it should.
i
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Post by Norbo on Jun 30, 2008 18:40:16 GMT 1
Have you thourght about fitting a biger rad or a fan on the back of you lc rad . The 125 rad is very small .
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Post by K.B on Jun 30, 2008 19:10:46 GMT 1
It will run hotter because it has a bigger cc and producing a bigger bang,
The cooling around the barrel and the rad was designed for 125cc,
A bigger rad an fan are requried.
Is the jetting correct , if its running a bit lean it will run hotter, I would jet it a bit rich this will
help it to run cooler.
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Post by twostroker on Jun 30, 2008 19:41:40 GMT 1
It will run hotter because it has a bigger cc and producing a bigger bang, The cooling around the barrel and the rad was designed for 125cc, A bigger rad an fan are requried. Is the jetting correct , if its running a bit lean it will run hotter, I would jet it a bit rich this will help it to run cooler. ive done a plug chop and its running slightly rich (dark brow almost black) im going to try a brand new temp sender just to conferm its not just reading hot (i have tested old one in boiling water and seems ok) what i cant work out is, in the 1980's it was a fairly common mod to fit a autisia 175cc barrel and just run the stock radiator ,im going to try the sender first then if no joy il strip the engine again and if i cant diagnose the problem il have to try find a complete top end inc carb and air box as i cant see my 29.5mm flatslide will work well with a standard barrel has anybody got an old ausisia barrel and a standard one that they could compare the water ways in for me? |
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Post by tomitch on Jul 2, 2008 0:28:34 GMT 1
hi mate iv got a pic of my mk3 barrel and bigbore (iv been told its an autisa) barrel next to each other if you give me an email addy ill send it over
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Post by tomitch on Jul 2, 2008 0:44:33 GMT 1
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Post by sulli on Jul 10, 2008 12:28:28 GMT 1
Wat about the thermo stat ? |
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Post by twostroker on Aug 18, 2008 20:36:48 GMT 1
hi there, it sounds to me like you should try blocking the waterways imediately ajacent the water feeds to simulate the head gasket, hence making the water flow the long way round,i use silicone all over no gasket never had a problem im running a genuine autisia copper gasget now,its better it runs about 1/2 untill i give it a real thrashing then it creeps up to just under 3/4. a bigger rad is on my to do list,has any one fitted a bigger rad?im unsure of a suitable one that would be easy to make look factory fit? |
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Post by carlos on Aug 18, 2008 21:48:17 GMT 1
It may be easier to fit a cooling fan, which you could control on a switch, therefore if it's getting a bit hot, or you're stuck in traffic, or planning to give it a good thrashing you could switch the fan on? |
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Post by Norbo on Aug 20, 2008 10:22:45 GMT 1
It may be easier to fit a cooling fan, which you could control on a switch, therefore if it's getting a bit hot, or you're stuck in traffic, or planning to give it a good thrashing you could switch the fan on? Thats a good idea you could get one from a big 4 stroke at a breakers and wire it up to the battery and a switch on the bars . Good thinking batman ;D |
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Post by carlos on Aug 20, 2008 17:11:18 GMT 1
I just think it'll be easier to make a bracket to mount a fan on the original radiator mounts than try to get a bigger radiator to fit! Also, the radiator gaurd will fit over the standard radiator!
Just remember to make sure the wires are the right way round on the fan or the air coming through the radiator will be blowing against the air coming from the fan creating stationary air which will make the bike overheat!
I don't know whether there would be any pumping issues with a bigger radiator???
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Post by carlos on Aug 25, 2008 19:53:47 GMT 1
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Post by carlos on Aug 25, 2008 20:11:18 GMT 1
Hmmm, don't think a fan is effective at high speeds!
The radiator would be getting 5000 cubic metres of air through it at 50 mph! (I think)
So the fan may restrict it, but, I can't work out how to take into account the fact that the radiator isn't mounted square onto the air, and the effect of the radiator cover and front wheel restricting air flow!
See if it runs cooler without the radiator cover?
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Post by tomitch on Aug 25, 2008 23:42:03 GMT 1
i dont think the fan would make much difference tbh either and with that amount of air flowing though it at 50mph (theoretically with the cover removed) i think the main solution to the problem would be to fit a bigger rad i dont think there would be much in the way of pumping issues as preassure would still be there it would just take longer to build up. hope you sort the problem. |
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Post by racerd on Aug 26, 2008 23:19:38 GMT 1
i have a big bore barrel as well do you think there is to much liner in the cylinder bore ie 7mm thick all the way round that could be causing the cooling issue, you could try using a tzr radiator or
250/350 lc/ ypvs, is there any way to add a thremostat in your cooling system, what spark plug are you using,
ive done a plug chop and its running slightly rich (dark brow almost black) black is to rich and and what premix oil are you using and what ratio ie 50 to 1, 40 to1, 30 to 1,
did you run the big bore in right,
il have to try find a complete top end inc carb and air box as i cant see my 29.5mm flatslide will work well with a standard barrel
yes the 29.5 mm flat slide will work with the 10w00/10v00 set up i used a 32 mm round slide on my 10w00 barrel,
do you think the end of the pipe that joins the end can is too
small as this will cause piston crown temps to go up
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Post by racerd on Aug 26, 2008 23:42:16 GMT 1
ron supplied a matika piston kit and i trial fitted it to the bore before it went on the bike and id defenetly say the piston/ring is a perfect match for the bore size.i just want to get it sorted asap to enjoy the nice weather while i can,il let you know hou i get on with the copper gasget when i get it . did you measure piston to bore clearance and piston ring end gap with feeler gauge, have you ever though of having coolant way around the exhaust port |
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Post by tzrman1984 on Jan 3, 2009 16:42:53 GMT 1
is there any updates as i have found myself quite involved in this topic and would like o know how and if he problem was sorted ?
peace out!!
lol
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Post by twostroker on Jan 4, 2009 19:26:59 GMT 1
well its sorted now,at the time the weather was hotter and ive changed a few bits so im unsure exactly what the problem was,im pretty sure its this,
as my motor is 50cc bigger and has altered ports it was a complete mismatch with the swarbrick pipe i was using,it made 13 bhp on a charity day dyno.i looked in to exhaust dimentions and the swarbrick was to small in a few places so i had a 1 off pipe hand made for me to suit the exact spec of my motor,it goes loads better now and it also runs cooler,i havent had it dyno'd again as i havent had the time or spare cash but if you get it in the power band in 2nd,it will go right through the box istaying in the band untill it goes off the clock in top gear.again i havent held it flat out in top but its on the standard gearing and id say it should do 110mph on the clock therefore a genuine 100mph,i prefere acceleartion on these small bikes as ar 80mph plus it doesnt feel the safe on a a 24 year old bike lol
if any bodys interested i could post up a new pic of my bike with the new pipe?
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Post by elsie1411 on Jan 4, 2009 22:27:56 GMT 1
may be completely irrelevant but sounds like an artical in classic motorcycle mechanics a couple of months back a guy installed a 500 rg motor into a rgv 250. Engine bored out to 570cc with 250 radiator and experienced servere overheating and then siezure turns out he was using the wrong coolant mix he was using 100% coolant and it needed to be a 50/50water mix.
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Post by tzrman1984 on Jan 5, 2009 13:20:52 GMT 1
wheres the piccies !!!
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Post by twostroker on Jan 5, 2009 19:51:39 GMT 1
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;D 
