Jump to content

Aprilia RS257


wazrs257
 Share

Recommended Posts

Off the top of my head I think its an NGK B9EG, 10's are recommended. Its an old ex-race plug, so I think its overdue a change. Running 33:1 pre-mix, I used to run 25:1 on my LC's years ago, so this isn't overly 'rich'. I'll try again tomorrow, with a fresh plug, & after checking the whole bike for loose nuts!

Strokers :tumbleweed:, but are more high maintainance than women!

Tell me about it! I've been using some B10EGV's and have been pretty impressed. They're not cheap though, the electrode is much thinner which helps stop it fouling I think. If you go too cold with the plugs they can become a bit of a pain to start. I've had bikes in the past that I've had to start on a set of 8's then once its warmed up swap over to the 10's. Bit impractical though.

Link to comment
Share on other sites

I'd always expected this build to be impractical. My current thinking involves, draining the coolant & removing the plug after a ride, then filling with a kettle of warm water (to reduce warm up time) & clean plug before riding. Warming up with one plug & racing on a harder one isn't something I've needed to do since I raced karts xxxx years ago! Might have to get used to it again.

I've mapped an IOM lenght circuit round my local area, this bike was built for a couple of IOM laps at 6am on a sunny sat/sunday.

Some work to do I think!

:icon_bounce:

Link to comment
Share on other sites

I've just got back from its second unofficial road test......f*@k me, its mental!! :D:rock:

Everytime it hit the power it lifted the front wheel & went balistic, unfortunatly the lanes round me are bumpy as hell, so was bouncing off the lock stops all the time! I'd forgotten just how much FUN 2 strokes are!

I love the smell of 2 stroke in the 'morning' :(:eusa_think:

It seems to be running rich at the moment, as it can be bump started with no choke, with ease. I'm going to leave the main jet as it is at the moment, buy may drop the needle a couple of clips, as it doesn't want to rev without using full throttle. Does anyone know of a decent dyno in the Warwick/Leamington/Coventry area? preferably with an operator thats experienced with strokers.

^_^

Link to comment
Share on other sites

It seems to be running rich at the moment, as it can be bump started with no choke, with ease. I'm going to leave the main jet as it is at the moment, buy may drop the needle a couple of clips, as it doesn't want to rev without using full throttle. Does anyone know of a decent dyno in the Warwick/Leamington/Coventry area? preferably with an operator thats experienced with strokers.

:D

Personally, I wouldn't bother trying the bike on a dyno, not yet anyway.

I'd try a smaller pilot jet, for the starting, raise the circlip on needle one notch at a time to sort part throttle and do a plug chop before changing the main jet.

Link to comment
Share on other sites

Alrite chap sounds like its a right laugh,

If you don't mind travelling a bit further, Jebs Performance in Shipston on Stour, south of Stratford. Jons specialises in sidecar outfits and i know hes done a fair bit of work with TZ motors.

I remember we had a TZ750 outift on the dyno, sounded like all the beasts off hell being unleashed, evil thing :icon_puke_r:

Cheers

Chris

Link to comment
Share on other sites

Alrite chap sounds like its a right laugh,

If you don't mind travelling a bit further, Jebs Performance in Shipston on Stour, south of Stratford. Jons specialises in sidecar outfits and i know hes done a fair bit of work with TZ motors.

I remember we had a TZ750 outift on the dyno, sounded like all the beasts off hell being unleashed, evil thing :D

Cheers

Chris

Thanks for that Chris, have just been looking at their web site, they're a diffinate possibility!

I 'weighed' the beast last night, using the scientific method of putting each wheel in turn on a set of bathroom scales. It appears to weigh about 106kg wet, my target is 100kg, so nearly there! Need to find somewhere to weigh it properly before I start boasting too much though.

:icon_blackeye:

Link to comment
Share on other sites

Thanks for that Chris, have just been looking at their web site, they're a diffinate possibility!

I 'weighed' the beast last night, using the scientific method of putting each wheel in turn on a set of bathroom scales. It appears to weigh about 106kg wet, my target is 100kg, so nearly there! Need to find somewhere to weigh it properly before I start boasting too much though.

:icon_blackeye:

try one of those weigh bridges that are near the motorway, ask them and they might be able to weigh it for you. also some garages now have scales.

Link to comment
Share on other sites

No Worries mate, Jon is a top lad but a hard task master to work for, i've never made so much coffee in my life!

I think he might be moving soon but its not far away.

I also used the extra scientific bathroom scales and block of wood technique and got 102kgs with a 3/4 kg heavy bias to the front on mine, sounds like were both heading in the right direction

:icon_blackeye:

Link to comment
Share on other sites

  • 2 weeks later...
try one of those weigh bridges that are near the motorway, ask them and they might be able to weigh it for you. also some garages now have scales.

I thought about a weigh bridge, there's one about 1/4 mile from my house. My only concern was that they're for weighing wagons & might not be very accurate for weighing something this light. Worth a thought tho, thanks.

No real progress to report at the mo. I've added an air bleed to the top rad hose and raised the header tank 40mm to increase the head. Should make filling with coolant easyier.

As for the running, I dropped the needle down 2 notches but this seems to have had no real effect to the part throttle performance. It was noticably 'crisper' when I returned from a brief ride, so maybe it needs to be warmed up for longer before it'll run right. Does anyone know how long a 250cc, 2 stroke single takes to warm up properly? It only got to about 45 degrees on the Sciusu temp gauge.

:eusa_dance:

Link to comment
Share on other sites

I thought about a weigh bridge, there's one about 1/4 mile from my house. My only concern was that they're for weighing wagons & might not be very accurate for weighing something this light. Worth a thought tho, thanks.

No real progress to report at the mo. I've added an air bleed to the top rad hose and raised the header tank 40mm to increase the head. Should make filling with coolant easyier.

As for the running, I dropped the needle down 2 notches but this seems to have had no real effect to the part throttle performance. It was noticably 'crisper' when I returned from a brief ride, so maybe it needs to be warmed up for longer before it'll run right. Does anyone know how long a 250cc, 2 stroke single takes to warm up properly? It only got to about 45 degrees on the Sciusu temp gauge.

:lol:

I'd be wary of taking it into the power band with anything less than 55 showing on the temp gauge and would probably try to keep the temp below 85 degrees. What coolant are you using?

Link to comment
Share on other sites

I ran my mito350 on straight water at first and it ran really cold. I know it's a pain but try a 50/50 mix of water and coolant, you'll be surprised how much less efficient coolant is at actually keeping an engine cool. You can fine tune the mix of coolant to water to get it to run at the temperature you want. Also I don't know what model RM motor you're using but I'd imagine it doesn't have a thermostat, this means that it will take longer than a road bike to warm up because it is pumping the coolant round the motor even when it's cold.

Link to comment
Share on other sites

Its a Rotax 257 kart engine not an RM. You may be thinking of El Gringo's RG125/RM250 hybrid.

There isn't a thermostat fitted at the moment, but 45, 58 & 70 degree ones are availible for this engine. I think I'll see if I can track down a 45 degree one as a starting point.

Had a part worn Dunlop D209GP fitted on the front today. The place that fitted it also does mot's so I had a word about them doing mine. They do 'day time' mot's no problem, but mine doesn't even have a stand or any means of starting it apart from bumping, but they said that would be no problem either! Happy days! It may still be ready for the Shoulder of Mutton meet a week on sunday after all. :D

Link to comment
Share on other sites

Ahh sorry my bad, too many two stroke projects! To me 45 degrees seems on the cold side but the tolerances in the kart engine may be much tighter than in a bike motor so capable of running cooler, two strokes in general can have more power squeezed out if they're running cooler.

Link to comment
Share on other sites

Also I don't know what model RM motor you're using but I'd imagine it doesn't have a thermostat, this means that it will take longer than a road bike to warm up because it is pumping the coolant round the motor even when it's cold.

Aye, that'll probably be mine but its good info anyway as i hadn't thought about thermostats and running temps.

About 65/70 ish is ideal i guess.

Waz, Good news on the MOT :shock:

cheers

Chris

Link to comment
Share on other sites

Waz, Good news on the MOT :thumbsup:

Good news about the feasibility of an mot! I've got to sort a few jobs before I can actually take it in for the test. When I discussed with them doing an mot for me, the guy was more concerned with the lack of kickstart than anything else. I recon I could bump it in the length of the test bay though! LOL!

Link to comment
Share on other sites

Just seen this on ebay, "believed to be the only working rs125 with this engine conversion in the country"!

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...e=STRK:MEWAX:IT

:pb2:

probably the shittest pictures on an advert ever. Nice mohawk man. Yeah collect as much as i can from a Kart racer who is going to make a pipe for it for me too

Link to comment
Share on other sites

I went into the bike shop thats going to do my mot today, in search of the best fully synthetic, premix oil that they had. I was presented with a litre bottle of Motul 800 factory line, road racing 2T. I nearly sh@t myself when he told me the price, £19!! He must have felt sorry for me cos he only charged me £17 in the end.

Now, a litre of oil at £17/litre, @ 25:1 gives 25 litres of fuel, or 68p per litre. Super unleaded at my local Shell station is £1.25 per litre, so with oil, makes it £1.93 per litre. Thats £8.78 per gallon!!!! Gulp!

:eusa_pray:

Link to comment
Share on other sites

Fingers crossed you're not going to need octane booster as well then.... :(

As an alternative oil you could try something castor based which the kart boys seem to swear by. Shell Kart M is fairly easy to get hold of and not too dear. I use morris MLR30 which you can get in gallon tins from the morris website, I think the price per litre comes out at under a tenner even after postage. There are a few more practicality issues with using a castor oil but IMHO these are outweighed by the hotter the oil gets the better a lubricant it becomes (as opposed to synthetic and mineral oils which turn to water when they get too hot) and then most importantly the smell!

The rate at which two strokes generally use fuel means that economy is never going to be a strong point, smiles per miles however is usually unbeatable though!

Link to comment
Share on other sites

I've decided that, instead of going for a blast today, Im going to try & sort out the rough running.

The guy that built the exhaust for me has had alot of experience of setting up these engines in karts, he told me to check that the fuel shut off valve in the carb is big enough to flow 0.8 litres of fuel per minute. It follows that in order for the shut off valve to flow at this rate, the petrol tank must be capable of flowing at least this much.

To test this, I timed how long the fuel tank took to flow 1 litre of fuel. I repeated this test 3 times, once with the fancy aftermarket fuel cap that is currently fitted, once with the standard fuel cap, and once with the standard cap open. The results were:

Aftermarket cap 1:51.4 minutes/litre

Standard cap (closed) 1:52.3 minutes/litre

Standard cap (open) 1:47.5 minutes/litre

The highest flow rate (standard cap, open) only works out at 0.68 litres/minute. Although these tests show that the petrol cap breather isn't causing too much of a restriction, the flow rate is no where near high enough. I have concluded that the restriction must be in the fuel tap rather than the cap. In order to test this, I have turned up an ally boss that bolts directly to the bottom of the tank, completly doing away with the fuel tap. The bore of this boss is slightly bigger than the bore of the fuel inlet on the carb, so hopefully this should be capable of flowing as much fuel as the carb. I just need to turn an o-ring groove & drill the 2 mounting holes, then I should be able to fit it & see if this has solved the problem.

Hopefully I'll be able to report some good progress later today!

:thumbsup:

Link to comment
Share on other sites

This picture shows the 'boss' I made to replace the standard fuel tap:

4737783133_bdfcede092_b.jpg

With this fitting in place, a litre of fuel took 42.6 seconds to flow. This is equivalent to 1.4 litres/minute. A significant improvement to the previous best of 0.68 litres/minute.

This is not an ideal solution for a number of reasons:

1) There is no way of shutting off the fuel flow except by using the dry break fuel connector.

2) No 'reserve' facility.

3) The standard tap has a 'strainer' to stop sh1t from the tank reaching the carb. I now have half a gallon of fuel full of paint particals due to the previous owner/idiot painting the tank cover & overspraying the inside of the tank! When I bought the tank on ebay it was described as being sprayed by 'a drunken monkey'!

I think the ideal solution involves either a CR500 petrol tap (do they have a reserve?), or a Pingel high flow tap.

Any suggestions?

:icon_salut:

Edited by wazrs257
Link to comment
Share on other sites

This picture shows the 'boss' I made to replace the standard fuel tap:

4737783133_bdfcede092_b.jpg

With this fitting in place, a litre of fuel took 42.6 seconds to flow. This is equivalent to 1.4 litres/minute. A significant improvement to the previous best of 0.68 litres/minute.

This is not an ideal solution for a number of reasons:

1) There is no way of shutting off the fuel flow except by using the dry break fuel connector.

2) No 'reserve' facility.

3) The standard tap has a 'strainer' to stop sh1t from the tank reaching the carb. I now have half a gallon of fuel full of paint particals due to the previous owner/idiot painting the tank cover & overspraying the inside of the tank! When I bought the tank on ebay it was described as being sprayed by 'a drunken monkey'!

I think the ideal solution involves either a CR500 petrol tap (do they have a reserve?), or a Pingle high flow tap.

Any suggestions?

:thumbsup:

i might have to take a closer look at what you are doing here as i am having problems with fuel starvation on my bike, however that is because the tap is a vaccum one and my carb doesnt offer that function so i have had to make something up to address this issue, from what i am looking at in your project it seems that replacing the fuel tap could be a very good option for me.

i dont think you really need a reserve function but the new model rs125's have a fuel level sensor in them, on mine i have it disconnected as my loom doesnt work with it

Link to comment
Share on other sites

i might have to take a closer look at what you are doing here as i am having problems with fuel starvation on my bike, however that is because the tap is a vaccum one and my carb doesnt offer that function so i have had to make something up to address this issue, from what i am looking at in your project it seems that replacing the fuel tap could be a very good option for me.

i dont think you really need a reserve function but the new model rs125's have a fuel level sensor in them, on mine i have it disconnected as my loom doesnt work with it

Couldn't you just fit a non vac fuel tap? I seem to have one thats of no use to me now, if you want it?

A fuel level sensor would be useful, but my bike has no loom/electrics to run it. At the rate my bike uses fuel (1/2 gallon for the 8 mile round trip to the mot testers!) I think some kind of facility to monitor fuel use would be good! Also as I said, a proper fuel tap has a strainer, I could just use an external filter but think it would just block up really quickly.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...