Vez

Just a little annoyed at the moment and it doesn't take alot to set me off on a rant at the best of times. I'm not willing to continue a discussion about the pressure aspect of water and coolant in a bike, its just too much like being at college and its still the holidays yet! In an emergency i would pee in my system to get me home (used canal water to get 5-6 miles home once) I've heard of the airlock bit causing issues, but never knowingly experienced it myself. Only way to check would be to measure the amount of coolant that the bike takes from empty at a guess. Also i believe some bike garages have a machine to remove the air from a cooling system (a bit like a brake bleeder) but can't say i have ever seen one. I swear you have pedals on your DTR with the temps it runs OG! The 250 main jet maybe the reason. I'm willing to bet that my hot RE runs a 210 main jet and with the cat stopping proper flow of hot exhaust gases it may explain a little. Vez.

Andy, Have you re-torqued the head nuts since fitting the gasket and running the bike a while? With the bike only having done low miles since the gasket was fitted i wouldn't think it was the coolant unless it is 100% tap water and is being revved high and ridden hard/abused as it was in the case i witnessed. With the coolant i use there should be at least a 50% coolant 50% de-ionized water mix. There are warnings on the bottle about lower ratios causing engine damage over time. I can't see a compression tester showing up a small head gasket leak, as i would expect a leak to open up as the bike gets hotter and parts expand, but i may be wrong. Personally i don't trust the piece of glass and sandpaper method to fix a warped head. It has to be plate glass and not rolled glass (it has ripples from the rolling process) and also at least 1/4" thick to stop it flexing under pressure. Even then i wouldn't be too confident it would sort a warped head out. An engineer skimming it is the only certain method imo. If you have the head skimmed (which you probably should) you may as well take the barrel along and have that done to get a good mating surface and up the compression slightly too, imo that is. Vez.

Tap water on its own will boil and expand at a lower temperature than it will when mixed with coolant (anti freeze as it is called on here). Water alone turns to steam and is expelled out of the expansion points and will boil dry if not changed or coolant added to a good ratio. Coolant has a faster heat transfer rate than water alone and mixing the two will change this rate depending on the ratio of water to coolant. Not using coolant at all will effect the cooling efficiency of the engines cooling system and increase the potential risk of damage to the engine, like for example a blown gasket (gaskets will expand faster being thinner) or even a warped head (if left unchecked long enough) as the metals of the engine will expand more than they would under normal designed operating temperatures. Also coolant should not cause corrosion as it is designed not to with the anti-corrosive additives it has, but mix tap water with it and it has the potential to do so, which is why it is advised to use de-ionized water to mix with coolant which has less potential of causing corrosion. I have witnessed first hand the expansion cap be blown off a DTR when tap water alone was used instead of coolant, when there were no other problems with the bike before or after (once the water was changed for coolant). Just because I made a bad call with the OP, it doesn't mean I just pulled the tap water issue out of my ass. Why not try it out if you doubt me and run your bike for a while with no coolant and just tap water, then maybe post back here and show the result In my eyes it is easier and cheaper to check the issue is not caused by a bad coolant ratio or other possible cause, than to strip the head down every time it starts blowing coolant out of the expansion bottle overflow. £10 for coolant and 10 min changing it compared to £25 and a few hours changing the gasket and coolant is a no brainer imo. This thread makes me wonder how many head gaskets have been changed along with the coolant and the problem "fixed" and the cause attributed to the gasket, without the coolant given a second thought. A slightly different jet size won't cause overheating, but one that is way to small will cause a lean mixture and will cause overheating. more fuel = cooler engine . more air = hotter engine. If you do have a blown head gasket Andy, then if it were me I would look into what is causing it to blow, otherwise you may keep changing gaskets, instead of finding the cause. Vez.

Yeah I'm fine, well better than the bike that is . All the right side is trashed, will up some pics when i am up and about again. I won't be going to Stafford, thought it best to say now than later.

Hey Ivan, Welcome to the forums. Vez.

At this point I won't be going after being knocked off the DTR on Tuesday night . May be getting a rental bike from the insurers, I'll let you all know next week. Thought you were going to Stafford on the Sunday 25th? Vez.

Good to hear you have sorted it. The carb is heated and with no thermostat this will take longer to happen, may explain the flat spot. Vez.

OG

The Pv cables don't look crossed, watch around the 17sec mark. The video has got clearer now it has been on-line a while, i noticed they get better with age when i made the one about posting pictures, probably Youtube trying to get the video on-line fast so it starts at lower quality until its been fully processed. After re-watching the video it does appear the valve works anti-clockwise(correctly) near the end of the pv footage, but at the start it does go clockwise. Has the green and black wire been earthed on yours Andy?

The PV's looked the same on initial investigation, i have since seen that the end part that connects to the servo pulley is different on the DT125RE, but that is the only difference. The servos we haven't compared for things like part numbers and number of wires. I'm 99% sure that mine has 5 wires and the same for OG's. There isn't an external servo controller, so i can only presume that it is either built in to the servo itself or is part of the CDI. I think its probably the former on the 5 wire version of servo, and the latter on the older 3 wire versions.

Here's a DTR one i cut open a while ago. I gave up on removing the parts as it would be easier to build one from scratch. I presume the DT125RE is the same internally.

You got a link for that Andy ?, I was looking into buying one of those MD80's but the cheapest i found was £60. I'm sending you a PM about the interview, may take me a few mins to write!

I gotta get me one of those invisible cool sounding silencers! The question of can you put a newer PV servo on a 02 bike is no at this point. It looks like the RE's rotate clockwise. I'll keep my eyes peeled on ebay for one for you Andy.

Hi Thanasis Welcome to the Forums Vez.

If you get the video posted of your servo operation Andy, that will answer both your question and mine about the newer servos.

I will get some together this week, need to de-coke the exhaust port anyway. I'm in no rush, just interested on how they compare

No such thing as silly question about bikes imo. Everybody has to start somewhere. My favorite saying is " Share what you know. Learn what you don't" Vez.

Sounds like a good idea. You offering to get your tools and camera out then ?

Just try the bottom 4 bolts on the fork legs (2 on each leg on the bottom yoke) and see how its goes. It should give you enough play to straighten the wheel, you may have to get the bike on a stand and slacken all the bolts (4 on each leg) and the nut on the top if it doesn't give enough. And yes, tighten everything up again after.

I think thats what I'm going to try Cynic Is that an RD350 book, just out of curiosity ?

Providing nothing is actually bent, you may have to also slacken the fork clamp bolts to give some free-play before straightening the wheel up. You could also try by simply wedging the tire against a wall or other solid object and correct it by turning the handle bars, if that makes sense. Its what the guy at the mot station did with mine

For the tick over, are you adjusting the mixture screw or the throttle stop? I ask because 1 and a 1/2 turns in on the mixture screw sounds a little off tbh, why not try and set it at 1 and a 1/4 turns out and see if that helps, its easy enough to put it back to 1 1/2 again if it doesn't help. Beyond that I'm stumped atm.

Well got a reply from Yamaha, So are they saying the cables need to be crossed or are they politely saying its faulty. Vez.

Hey Dave, Welcome to the forums Vez.

The second one will fit although i cant say for sure it will run right without changing the jets in side.( a jet is a brass screw type component that has holes of a certain size in it, well basically, and are changed to various sizes for tuning purposes) Is your bike tuned in anyway? i.e like a after market exhaust (a DEP or big-one). or is it totally standard? Some pictures would be nice and maybe help to answer the above. Vez.