DR750 & DR800 owners thread

[motolab]

Originally Posted by Ladder106

If your slides require replacement, I was able to get mine from a BMW dealer. They are the same ones used on the early model BMW Funduro 650. BMW has these listed as a part number (slide and O-ring" while Suzuki makes no mention of this.

I thought you were talking about the slide guides rather than the slides.

Regards,

Derek

[motolab]

Originally Posted by Tim

I have just spent several hours on the carbs and one is still pissing fuel out

I went right back to square one and stripped them down, removed all of the O-rings and gave them a good clean, wash and dry. Dried everything and gave them a thorough blow through with compressed air. As I already mentioned I have replaced all of the O-rings and lightly lubricated them as I put the carbs back together. I set the float heights using a digital vernier calliper to get them as accurate as I could.

I stood the carbs on my bench and connected up my remote fuel tank, switch on the fuel and within a few seconds fuel starts to run out of the right hand carb. The fuel seems to come from this small hole.



I opened up the float bowl on the leaking carb and bent the float valve arm so that it was virtually closed even when upside down and them tried again - you guessed it! - still fuel leaking out so, how is the fuel getting into and overfilling the float bowl if the float valve is shut?

The rubber tip of the float needle should be inspected under magnification. It should perfectly conical, with no witness line evident where it was contacting the seat. If any evidence is visible, or if there is a gap between the bottom edge of the rubber tip and the aluminum portion of the needle, if the plunger is stuck, or if the plunger return spring is sacked out, the needle should be replaced.

The float height should be set to 14.6mm with a float height setting tool.

Regards,

Derek

[Ladder106]

Derek,

Thanks for keeping an eye on this thread.

It's always nice to hear from a pro.

I have a good friend in Apton. I'll have to make a point to drop by your place sometime since it's pretty much on my way there.

Appt. only?

[motolab]

Originally Posted by Ladder106

Derek,

Thanks for keeping an eye on this thread.

It's always nice to hear from a pro.

I have a good friend in Apton. I'll have to make a point to drop by your place sometime since it's pretty much on my way there.

Appt. only?

Hello Sir,

You were doing a pretty good job without me! And it is good to know that I'm not just annoying the heck out of folks...

Just let me know when you are coming. Lunch one day maybe?

D.

[Ladder106]

Lunch sounds great.

I meant Aptos not Apton.

I'll call first.

[Ladder106]

Well.....

It runs.

Everything works

Nothing leaks

Nothing fell off

I put in about 40 miles this afternoon. It's good to be back on the big bike again.

BUT

Rob was right. It's running rich.

Rob, the 800 seemed not really much different than the 750. Likely the fueling being off is affecting this a bit but my "Butt Dyno" didn't detect much change. It seems to pull a little stronger in 4th and 5th but is pretty rich on top .

It pulls nicely up to about 6000 in top gear then doesn't want to do any more. When I got back the end of the pipe was coated with a nice, dry, fluffy BLACK.

No oil, not wet (thank goodness) but veryvery black. Wipe it off with your finger and blow most of it off.

So, I guess tomorrow the carbs come back out and 125 mains go in.

Carole reminded me that I LIKE taking motorcycles apart. I needed that cause I didn't want to do it all again but I have to do it right.

More later.

[robmoto]

Ray good to see its a goer, after changing the jets tomorrow if still not much difference open up the end of the can to at least 35/38mm or in your imperial talk 1 1/2 inches through the baffle so you carn,t find it ever again and put in one of lars,s mesh inserts that he makes for pro duo mufflers but they allso after looking tonight at mine that I am now fitting to the blue bike that GPR oval muffler I believe you have one too it looks like the mesh insert will go straight in, there, 1 inch or 25mm hole just aint big enough it slowed my now 800 yellow bike down.
Or just take the baffle out and go for a small ride with ear plugs and see what happens , you may gain that bottom end and mid range power where we ride most of the time.
Just for a tempory thing you could get some mesh stuff and snip and fold it arround the end of the tail pipe of the muffler and hold it with a radiator clamp to give it a tad of back preasure and keeps the cop.s away while testing .

[robmoto]

RAY is your fuel called E 10 I believe its octane rating about 93 I never use it but run all my bikes on 98 just thought I would mention it I have never tried the what we call the standard petrol unleaded 91 octane because it starts to go off after 4 weeks I am told and some of my bikes sit for months so no good for me.

[Ladder106]

Morning Rob,

Thanks for the tips. Thinking about it last night, I believe I'll see if I can try different exhausts first. I have a Laser (from the DR800) and still have the GPR. I thought I'd pull the "quite" inserts out of one or both of those and give the bike a run. It may be that my GSXR pipe is a bit restrictive. The only problem is that the GSXR can is the only one that I can make "US Forrestry Approved" with the addition of a mesh spark arrestor...the other pipes are street only. Runing this bike in the wild without the arrestore nets you very large (in the order of $1500) fines from our Rangers.....and rightly so. You guys down in Oz know all about wildland fires.



Changing the pipe should also confirm that I am, in fact, running rich....but the black at the end of the pipe is a pretty good indication.

If nothing else, this does show me that the airbox on the SR41 is truly restrictive. I keep putting off carving mine up but it seems inevitable.




Our mandated Repulic of Kaleeforneea fuel is called "E10"

It's 10% ethanol....if you're lucky. Some of the cut-rate stations have been known to pump more corn squeeze than the name brands.

I tend to stick with Shell or Chevron but the highest grade fuel we can get is 91 octane (measured ROM).

I also use Startron enzyme treatment to try to damp down the effect (collecting water for one) of the alcohol.

I think it's a misguided attempt by all the treehugger (who for some reason tend to drive SUVs) to save the earth. Our government just sees a way to subsidize all the corn farmers in the midwest.

Anyway...it's rubbish. A few months ago the tree hugger lobby in league with the air quality nazis cooked up a plan to go with 15% ethanol....until all the major auto builders told them they be rebuilding their SUVs after 10 thousand miles.

In the real world, I don't know how this affects jet numbers and is one of the reasons why I try not to recommend jetting to guys overseas.

[Ladder106]

So my shop didn't have 125 main jets.

But...I have a pair of 120 and one (1) 127.5.

So since 125 X2 is 250

and

120 plus 127.5 is 247.5.......

.....I'm going to try putting different main jets in the carbs.

They don't differ that much and with my understanding of physics there should not be that much of a flow difference between the two carbs.

Both carbs go to the same place....so I'll give it a go.

I also discovered that the float bowls can be dropped by removing the exhaust system and working from the bottom.

You have to use a few "creative" screwdrivers and it helps to have allen bolts holding the float bowl on....but it's much easier than carb removal....particularly when you've spent 2 hours making certain they are attached correctly.

So....opinions or idea about running different size main jets.

I'll post results.

[robmoto]

Ray one side of your piston will be rich and the other side lean your piston may split down the middle .
personaly I would get the right ones, using 91 compared to 98 meens your bike will be a fraction leaner .
try taking the snorkle out and or open up the side of the air cleaner by cutting it a triangle shape might help you too.

[Ladder106]

Yeah, I'll get the correct jets. Just want to try it like this for interests sake.

If patience is a virtue, then, maybe impatience leads to invention.

I was so excited that I could actually take the float bowls off from the bottom without removing the entire carb that I figured I'd just put these jets in and ride back to the shop tomorrow for the correct ones.

I'm sure there's enough turbulence in a 4 valve head to mix the gasses up to compensate for any slight difference the jets would cause and I'd expect the net result to be pretty close to running 2 125 mains. Plus I think I'll get one of those overbore pistons from Mait to have on hand...if mind cracks down the middle.

I've thought about opening the side airbox but most say that doing this makes the bike sensitive to cross winds leg position etc. I have an old filter that's not too dirty so may try it there first.

[robmoto]

RAY maybe for that extra little bit of air and still using the snorkle , you can drill some holes in the remaing part of the triangle bit all these little things add up in the end , and allso did you file or grind the head so it lines up perfectly with the inlet manafolds .
The bike I am doing now these were 1.5mm or about 1/16th out of allignment, but only on one side.

[Ladder106]

Intake boots and cylinder head castings lined up very well on this bike.

I always check for this.

It wasn't up to a professionally "ported" head standard but pretty close with no large gaps or lips for the gasses to trip over.

I also check the welds between the head pipe and the attachment ring that mates to the head as I've found that some bikes have a significant restriction at this point.

Have a few chores this morning, then will give my "Unequal DR" a run back to the shop for the correct bits.

One this I did notice while riding yesterday was a very slight sideways slip int he rear tire when accelerating away from a corner apex. Twice to the left and once to the right.

I think this means that the 800 engine is pulling just a bit stronger than the 750 since the 750 engine never spun the rear wheel like that unless is was a conscious effort to do so and usually only on gravel or dirt.

[Ladder106]

Jetting update.

Well..another day....another test ride.

The two different jets (1-120 and 1-127.5) ran OK but no real improvement in top end.

I've done a bit of research and discovered a few points. These things are likely obvious to the more experienced Big owners but a bit of interest to me still so I'll share.

Reading the service manual I discovered that the main jets for the SR41 were 120. When the SR42 (800 cc engine) was put in using the same frame and airbox as the SR41 the standard main jets used were 117.5.....so actually leaner.

This certainly supports Robs statement that when I put the 800 into the 750 frame (using the smaller airbox) that the bike would need smaller mains.

The other fact I discovered while searching the DR650 sites regarding the GSXR 1000 silencer was that the STANDARD main jets on the DR650 should be made SMALLER (leaner) if the GSXR silencer was used on the 650 with no other mods to the airbox or carbs. This supports what Bluesman has been saying all along that you have to have a large volume silencer for this bike. What complicates things for me here in the western US is that I MUST have a spark arrestor on the bike to ride anywhere off-road. The GSXR pipe supports the spark arrestor nicely so I'd really like to keep using it.

So now I have an engine that wants smaller mains and a silencer that wants smaller mains.

I have 125s in now and am thinking about going right back to standard jetting for a SR42...that being 117.5. I think I have those jets in the box.

I'll play with it tomorrow and see what happens.

So, even with you lot beating me over the head with information, it's still taken me over 3 years of Big ownership to learn stuff.