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Old 07-31-2012, 10:24 AM   #2956
Earthscape
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Quote:
Originally Posted by Lenz1 View Post
Hi Guys

... I don't get the manufacturers intent here other than to restrict output...
Their intent may have been to increase intake velocity as it's entering the cylinder head. Don't really know, but it will be interesting to see what your experiment finds.
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Old 07-31-2012, 02:43 PM   #2957
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Their intent may have been to increase intake velocity as it's entering the cylinder head. Don't really know, but it will be interesting to see what your experiment finds.
But if the manifold steps down to 24mm and the inlet on the head is 28mm then there's a bugger of a turbulence causing ledge there.

Even using jb weld to build up the inlet to 24mm and tapering back would provide better flow.
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Old 07-31-2012, 06:45 PM   #2958
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The restricted intake boots got debated for years on ThumperTalk. I seem to remember the debate started after one of those bike spec web sites posted a hp rating of like 17 for XT350's. From everything I read the restricted intake boots were a European and maybe even Canadian thing. I have seen European parts schematics posted that do show two part numbers for the intake boots. Some say it was for restricted licensing (which makes sense to me) and some say it was for emissions.

I have no idea which is true. But apparently it is true that restricted XT350's (or TT's overseas) were sold in other countries. However, I have looked at the parts schematics here in the US and there was only one part number for those boots for the entire run of our XT350's. So we didn't get the horsepower restricted models. We just got ridiculously lean jetting and that bastardized YDIS carb. So ordering a set of intake boots from the US should bring a restricted bike up to the full horsepower spec.
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Old 07-31-2012, 08:49 PM   #2959
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I don't think he's talking about the restricted intakes. I saw a picture of one . There is no mistaking it. Half the intake is blocked off. I think it was on the airbox side. Not sure though.
I noticed the mismatch of the boot and the head also. I opened up the boot side a tad and filed the edge down to match the head. No idea if it made a difference. That kind of stuff bugs me so I just take care of it as I find it.
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Old 08-01-2012, 12:57 PM   #2960
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We got the restricted intakes for the XT's in the UK and it was to meet emission's regs courtesy of the EU. Oh and TT's are higher spec XT's not just a different model name for the same bike
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Old 08-01-2012, 04:46 PM   #2961
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We got the restricted intakes for the XT's in the UK and it was to meet emission's regs courtesy of the EU. Oh and TT's are higher spec XT's not just a different model name for the same bike
I thought it was to reduce the power output for learners?
Stock is about 22hp.

* Just checked and that only applies to 125cc or less and is 14hp. Although the restriction would drop it to about that.

Engine-wise the XT and TT are the same.

XT/TT = XL/XR
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Old 08-02-2012, 12:56 AM   #2962
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Nope just emissions, like you found learners can only have upto 125cc(and around 15hp max) and the XT made 17hp...bloody EU regs. There are little differences between XT and TT like the metal oil pump gear, most of it was better running gear and different plastics
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Old 08-02-2012, 07:07 AM   #2963
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Quote:
Originally Posted by NordieBoy View Post
I thought it was to reduce the power output for learners?
Stock is about 22hp.

* Just checked and that only applies to 125cc or less and is 14hp. Although the restriction would drop it to about that.

Engine-wise the XT and TT are the same.

XT/TT = XL/XR
Nope. The TT had bigger intake valves.
I think the Ausi TT was our XT. Or maybe it was the other way around.
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Old 08-02-2012, 11:59 AM   #2964
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Hello! Just pulled the trigger on a '92 XT350 from an old man who can't ride anymore. All stock, only 3000 miles and runs pretty well. I was able to blast around his property a bit, and aside from the severely underperforming rear shock, it seems like a decent, solid bike. I read through the pages of this thread, and so far, it looks like the rear shock/spring, aside from Works Performance building you a one-off at $700+, is a murky area. I also remember seeing some speculation that a shock/spring off a TT350 might work if the swingarm is also swapped. Can anyone confirm this?

I'll be doing the other normal mods, uncorking it and putting on a larger tank and rear rack, barkbusters, bash plate, emulators for the front springs, etc., but I'm also hoping to remove the disgustingly 90s blue and teal decals. I've got a heat gun, that should work, no? Also going to replace the pink fork boots with some black ones, recover the seat in black and paint the intake vents black as well. Right now, it's just too "Saved by the Bell" for me.

Also, perhaps I missed it and if I did I apologize, but does anyone have a link for an electronic copy of the service manual?

Looking forward to putting some miles and mud on this work horse.
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Old 08-05-2012, 03:22 AM   #2965
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TT 350 rebuild

Hi All

So the project moves on with some major re-development of the cylinder head and designs for the inlet tract progressing.

The head in stock form had significant protusions of cast alloy downstream of the valve seats ie into the combustion chamber plus major ledges within the inlet ports, upstream of the valve seats. So I've massaged the inlet and exhaust ports and the valve seat "lips" very carefully to leave sufficient depth of alloy behind the valve seats to absorb the loading stress plus avoid touching the existing seat faces with the tungsten carbide tool. My apologies for a lack of pics at this stage.

My nephew who previously owned and serially molested this bike, supplemented engineering with silicone and dropped the 2 outer layers of the head gasket (3 layers) to raise the compresion ratio. I can't find any squish data for the std head gasket Vs valve to piston clearances but it appears deleting the outer layers of the head gasket loses around 18 - 19 thou without any evidence of collision between piston and valve. So I've now had 20 thou (~0.5mm) milled off the head, with the intention of a compression ratio ~ 9.7 . There may be an increase in engine temperature due to the compression increase but I've acquired 2 oil coolers from early Mitsubishi Pajero 4WD's with nicely open finning for the high load / slow speed / low air flow work .... we'll see how that works out. Maybe better than the single, closely finned Earl's oil cooler fitted as std on the TT350.

The people at ProPort in Rockhampton, Central Queensland did the valve / seat work - these guys are very capable and their workshop / knowledge base can handle ANYTHING. Allan runs the show.

The std inlet "boots" / joiners / restrictors are rubbish and will be dealt with shortly.

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Old 08-05-2012, 04:34 AM   #2966
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Originally Posted by Lenz1 View Post
There may be an increase in engine temperature due to the compression increase but I've acquired 2 oil coolers from early Mitsubishi Pajero 4WD's with nicely open finning for the high load / slow speed / low air flow work .... we'll see how that works out. Maybe better than the single, closely finned Earl's oil cooler fitted as std on the TT350.
Where would you tap the cooler in?
In place of the return line from the head?

The TT350 didn't come with a cooler from the factory.

A small DRZ250 cooler would mount quite tidily though.
I've got a spare DR650 cooler, but it's a bit big.
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Old 08-05-2012, 07:24 PM   #2967
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This bike is compliance plated 03/99 by Bert Flood Motors Pty Ltd Australia. The oil line to the top of the cooler comes off the oil filter casing @ 12 o'clock and the return from the cooler bottom taps into the same casing @ 5 o'clock. This may have been a mod for Australia but the existing cooler fits neatly within the std air scoop on the right side of the fuel tank.
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Old 08-05-2012, 07:52 PM   #2968
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Bike coughs and misses

I have an 89 xt350 with about 16K on er. Still runs great with one problem. It has developed a cough and I have to run with the choke pulled out about 1/4 of the way. Anyway I was looking at the boots that connect the carbs to the intake of the engine and they really look loose. I can move them to the point where I think it's suckin air around the boot.

Anyway where is the best place to get these rubber boots?
Can I replaced them without takeing the carbs off?
Should I expect a major problem getting the bolts that hole the boots to the engine out?

thanks for the help. I gotta get er back on the road. LOL

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Old 08-05-2012, 08:23 PM   #2969
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The boots are an OEM only item. Just got a set for my 1988 this year and they ran about $130 delivered to my door. I did not have any problem with the bolts at all. The carbs come off pretty easy. I tried to patch my boots first and had the carbs on and off four or five times. I got it to the point where I could pull them off pretty quickly. Don't try and patch them, just bite the bullet and buy the boots.

Good luck!
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Old 08-05-2012, 08:33 PM   #2970
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Thanks, any tips???

Did yours do the same thing mine is doing? Coughing and having to run with the choke part way on?

Where did you get the boots?

thanks

Gary
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