Thermostat bypass on 2 stroke ....?

Thermostat bypass on 2 stroke ....?

Author
Discussion

hebegb

Original Poster:

1,523 posts

146 months

Tuesday 28th March 2017
quotequote all
Right , genuine request for knowledge and info of any kind from those who know and have valid experience to offer , please .....
A coolant hose is a bit soft and baggy on the underside of the rads, a pipe connecting the two radiators and seemingly going to the thermostat housing on my 2008 KTM 250 EXC ( 2T).... it has been losing water once hot and under load and I think this pipe is the problem , but having tried my local KTM dealer the pipe kit is discontinued for this model and the only ones which seem available are Samco silicone thermostat bypass kits .....
What do I do , I understand the warming up procedure will need to be regimented if running this way , allowing thorough warming of the whole water jacket before use, but why does it seem that these are the only kits available and what would the relative concerns be of running this way ?
Many thanks for all input .

Biker's Nemesis

38,534 posts

207 months

Tuesday 28th March 2017
quotequote all
Have you tried Redline KTM Grahame?

podman

8,850 posts

239 months

Tuesday 28th March 2017
quotequote all
No ideas of the "why its that way" but its a common thing to bypass on a stroker, I had to on my YamaGamma(which repaid me by seizing anyway ..biggrin.....not cos the the plumbing thou) and most of the modded/ big bore RDs run without one, I wouldnt worry overly, as you have said, warm it up properly before you had off and all will be well.

Mr2Mike

20,143 posts

254 months

Tuesday 28th March 2017
quotequote all
Would it be possible to replicate the function of the original pipe using universal silicone hoses and an alloy T piece? I dont know what this pipe looks like, could you post a pic?

Unless there is a known problem with the thermostat id want to keep it working if at all possible.

Tom Logan

3,191 posts

124 months

Tuesday 28th March 2017
quotequote all
On every stroker I've had (quite a few, road and race) I've knocked the centre out of the stat rather than remove it completely. This will allow flow from stone cold whilst providing some flow restriction which helps cooling, which is good.

Just make sure it's well warmed up before making progress, cold seizures are nasty and happen without warning.

hebegb

Original Poster:

1,523 posts

146 months

Tuesday 28th March 2017
quotequote all
Guys , ever so grateful for the feedback - being a self-confessed stroker ignoramus I am pleased that the fact that I have gone ahead and ordered the bypass kit already, is not a complete waste of money and that nothing majorly to worry about ....thanks for the reassurances.
John - no, I haven't , but should have called you thinking about it ...I didn't know of them but shall call tomorrow and discuss , I guess they know you well , right ?
I like the idea of not losing the whole thermo and knocking the guts out but , the only pipes In the Samco kit do not offer the T piece option to do that , it completely removes it .

I was desperate to reach some form of resolution as really need to ride it this weekend without the option workwise of dropping it to a shop etc and waiting / hoping for a result as I mentioned the cooling system when it went in recently and got it back untouched in that area ( having also needed to remind them to change the gearbox oil on the morning of proposed collection ......the "good old bike game"... )....
Ah well - Awaiting Fed-Ex on the 'morrow....
irked

Biker's Nemesis

38,534 posts

207 months

Tuesday 28th March 2017
quotequote all
I'll text you Grahame, the walls have ears in this place.

powerstroke

10,283 posts

159 months

Tuesday 28th March 2017
quotequote all
hebegb said:
Right , genuine request for knowledge and info of any kind from those who know and have valid experience to offer , please .....
A coolant hose is a bit soft and baggy on the underside of the rads, a pipe connecting the two radiators and seemingly going to the thermostat housing on my 2008 KTM 250 EXC ( 2T).... it has been losing water once hot and under load and I think this pipe is the problem , but having tried my local KTM dealer the pipe kit is discontinued for this model and the only ones which seem available are Samco silicone thermostat bypass kits .....
What do I do , I understand the warming up procedure will need to be regimented if running this way , allowing thorough warming of the whole water jacket before use, but why does it seem that these are the only kits available and what would the relative concerns be of running this way ?
Many thanks for all input .
I have a 250 exc , If you are mainly off road it will be fine without the stat , winter on road it might run a bit cool
warm up stationary then ride , losing water may just be overfull or the rads are muddy /blocked or a gasket issue ,
if you do a bit of slow stuff a fan kit is a must without forward motion they can soon brew up without the fan ...

catso

14,771 posts

266 months

Tuesday 28th March 2017
quotequote all
I bought an uprated piston/cylinder/head kit for a 2 stroke Gilera and it was supplied with a 'thermostat replacement kit' - basically a washer to fit in the hole where the 'stat would normally go, presumably to reduce the bore of the opening to stop it running too cool?...

Steve Bass

10,186 posts

232 months

Wednesday 29th March 2017
quotequote all
powerstroke said:
I have a 250 exc , If you are mainly off road it will be fine without the stat , winter on road it might run a bit cool
warm up stationary then ride , losing water may just be overfull or the rads are muddy /blocked or a gasket issue ,
if you do a bit of slow stuff a fan kit is a must without forward motion they can soon brew up without the fan ...
Definitely look at the fan kit. If the bike is getting hot they do vent and loose water easily.
As said above make sure the rad fins are not clogged up or bent over.
As for the thermo bypass it won't hurt but in the UK climate I'd be tempted to keep it and run the fan kit.

hebegb

Original Poster:

1,523 posts

146 months

Wednesday 29th March 2017
quotequote all
Cheers Steve and all above with appreciated advice- suggestions...
The fan kit idea appeals, but mine is kickstart only and the only kits I see avaiklable are for elec.start models, however I am going to try the bypass kit, warm it up properly and see how I go on...
I think.
scratchchin

Steve Bass

10,186 posts

232 months

Wednesday 29th March 2017
quotequote all
Does the bike have a battery or any vestiges of road legal wiring like a reg/rec??? As an exc I'd have thought it would??
You might need to increase the battery size or reg/rec output to support the fan but not impossible.
And if you can have it activated by a thermo switch rather than a simple on/off on the bars.

hebegb

Original Poster:

1,523 posts

146 months

Wednesday 29th March 2017
quotequote all
No - no battery at all but it is road legal with lights - it is def. exc Enduro 2008 regd/ 2009 model when you use the Vin. on KTM parts microfiche .....
Bypass kit has landed and only three pipes so not even full replacement set to eradicate possible guilty party despite me being pretty certain it is the thermo related pipe from left hand radiator .....
Hmmmm.

Steve Bass

10,186 posts

232 months

Wednesday 29th March 2017
quotequote all
Ok, not a crisis.
I would fit the fan and connect to a constant supply so it's always on. You can then retain the thermostat to manage the temps.
And regarding the suspect pipe maybe samco have suitable pieces and joiners to fashion a replacement??

Yazza54

18,464 posts

180 months

Wednesday 29th March 2017
quotequote all
Going to go round and have a look at the bike later with any luck, Graham mentioned it's "using" quite a lot of water throughout a day enduroing, no visible leaks but some steaming etc.... Also if Kais changed the gearbox oil and the water ain't going in there via a knackered seal or whatever then where's all the water going?? My bet is in the engine.

If that is the case then may as well check the squish while we're at it. I believe the head gasket is o rings on these, anyone confirm? Think it's an 09 model.

Steve Bass

10,186 posts

232 months

Wednesday 29th March 2017
quotequote all
What's "quite a lot"?
Before you strip the motor try pressure testing the rads and check the rad cap. If the bike is getting hot on slower technical sections they do boil up quickly. Might be the rad cap venting too much or too readily

Yazza54

18,464 posts

180 months

Wednesday 29th March 2017
quotequote all
Steve Bass said:
What's "quite a lot"?
Before you strip the motor try pressure testing the rads and check the rad cap. If the bike is getting hot on slower technical sections they do boil up quickly. Might be the rad cap venting too much or too readily
He said it went through a litre Last time....! And the rad cap is new. At least the piston will be nice and clean biggrin

Steve Bass

10,186 posts

232 months

Wednesday 29th March 2017
quotequote all
Yazza54 said:
He said it went through a litre Last time....! And the rad cap is new. At least the piston will be nice and clean biggrin
A litre!!! Ok, there's definitely a bit of a problem biggrin
Loosing that much I reckon you'd spot the dripping or steam. So if it's not going into the gearbox (which can only hold so much) then it's heading out of the motor.
As you say..first suspect will be the head gasket.

Biker's Nemesis

38,534 posts

207 months

Wednesday 29th March 2017
quotequote all
Yazza54 said:
Going to go round and have a look at the bike later with any luck, Graham mentioned it's "using" quite a lot of water throughout a day enduroing, no visible leaks but some steaming etc.... Also if Kais changed the gearbox oil and the water ain't going in there via a knackered seal or whatever then where's all the water going?? My bet is in the engine.

If that is the case then may as well check the squish while we're at it. I believe the head gasket is o rings on these, anyone confirm? Think it's an 09 model.
Yep, base gaskets are paper/card/cornflakes box.

hebegb

Original Poster:

1,523 posts

146 months

Wednesday 29th March 2017
quotequote all
Well , folks , much kind advice and when I said stroker ignoramus , I really meant it ...
So , head gasket it may well prove to be , but , hopefully verified and sorted prior to killing the bloody thing .
Ryan, once again proving what a top chap he is and the meaning of true friend springs to mind ...and he always enjoys the slap up meal out with the respective Mrss, and the very messy booze fuelled capers we invariably end up in after such outings ...... he has exorcised my demons of horrible long term costly out of action repairs and brushed it off with his casual " it's not such a big deal , have it sorted in no time " nonchalance based upon knowledge and ability.

I am humbled by the willingness to help others by some people and the fact that I met Ryan through others on here and now very very good true friends abound - excuse me while I shed some biking happy tears , or , is this bath too hot and is my oversize ( 500ml ) glass of Merlot very nearly empty ....?
Cheers! smile