Honda XR650L: Re-jetting and Dave's Mod (What You Should Know Before Doing It!)

Are you planning on rejecting the carburetor on your dual sport bike or you want to do the Dave's mod on your Honda XR 650L

Now this video I chat about stuff I wish I knew before I did it and this is stuff that you won't see in the instructions so stick around

Hi I'm Franswer from Adventurebike troupe.com where we chat about bike riding, maintenance, travel tips and more

this video I want to chat to you about rejecting your carburetor on any bike and

doing the Dave's mod specifically on the Honda XR 650l now this is not a

technical how-to video step-by-step how-to video I'll link the exact steps for

the Dave's mod in the description below this is rather a video on my experience as an

amateur mechanic and what you need to look out for when you do the Dave's mod or

when you reject your carburetor. And this is stuff that I wish I knew before

and this is stuff you won't see in the instructions to Dave's mod or rejecting your carburetor

Now why would you want to do the Dave's mod on the Honda XR 650L

Now a lot of people will say there's a lot more power because you add bigger jets, you drill the slide

you shim the needle, so and there's the snorkel of the airbox

So there's a whole lot of stuff that you do to the bike to make it more powerful now whether you really get more horsepower

it's questionable I don't think it's conclusive a lot of people say it doesn't

make a difference it just runs better or there's better throttle response but the

main reason why I did this is because it's common knowledge that the Honda XR

650 is jetted lean from the factory to pass emissions test I mean it is an old

primitive engine air cool engine so the main reason why I did the Dave's Mod

is to reach in the mixture so that it runs cooler. Because for me reliability is way more important than power

And for me as an inexperienced dirt biker, there's more than enough power or torque on this bike to get into serious trouble

So it wasn't for the power, it was for reliability, especially to make the engine run cooler

Oh, and there's another reason. And this is probably, I'd say the main reason

It's just fun to fiddle with bikes. I mean, why would you buy an old primitive designed

bike like this and then not play around and fiddle and mod it if if you wanted a bike

that already runs good you can just buy BMW or a new Africa twin or something like

that or an EFI bike like the XT 660 R or Z so for some reason we KLR and XR

riders just like to fiddle with bikes and that's one of the main reasons also why

I did the Dave's model so like I said this video is not a step-by-step to

There others out there that pretty good I link it in the description below This is stuff that I wish I knew before I did the Dave Smart Now if you are anything like me You are not a an experienced mechanic but you like to fiddle with stuff and you always break stuff and learn stuff as you go along and there always something

you wish someone who told you before you did the job and that's why I made this

video because there's a couple of things that I didn't do right the first time

round and I've had this carburetor off the bike so many times and a lot of people will

say the XR 650 is fiddly with the jetting the original kind carburetor so it does

take some trial and error so this is what I want to share with you now the

first thing that you have to remember when you take out the carburetor is

cleanliness you have to work very clean so when you take off the carb wash the

bike first make sure that there's no dirt around the choke that you're gonna

have to take out and around the the boots on either side of the carbonator

where it fits to the airbox and to the intake manifold and then when you've got

the carb off you're gonna have to take off the top of the carburetor there's four screws there be very careful not to strip the screws they're very soft I'm still

waiting for replacement screws I didn't strip mine but you may want to replace

things so get them beforehand be careful when you take it off there's a diaphragm in the top so be careful not to pinch the diaphragm if that diaphragm

tears you're gonna suck air there and it's not ever gonna run right again so be

careful the diaphragm inside the slide which you are gonna drill out

Insliders slide there's a little plastic widget and it's very easy to strip this widget. I stripped mine

So with the Phillipshead screwdriver So luckily you can use a socket on it as well

Another thing is I damaged the spring inside everything is still working fine on that side

But just be careful as you take it out don't be in a rush always make sure you have enough time to do this job slowly and then don't stop halfway which I'll come to next

So the top that's what you look out on the top at the bottom again you remove the float

pole with four screws be careful not to strip those out be careful there's a little

rubber oaring around the side or wash around the side just take that out slowly

carefully and then clean out the carburetor very important you have to clean out

the floatball there was some gunk in mind which are just ignored for some weird reason

and then afterwards realized I should have cleaned it out properly because the

pilot jet hole is so small that any little bit of dirt that you dislodge will go in there

and will clog the pilot jet and it won't idle properly it won't run properly so

very important when you open the carburetor always be prepared to clean it out

properly so I took it out apart took it apart again I removed the gasket

from the float bowl and then I washed it out properly with the vinegar and water

solution and then sprayed it out again with carp cleaner and a little

tissue paper just to clean out every little speck inside also remove the drain

hole remove the fuel mixture screw and the all the the well the pilot jet

and the main jet remove those and then spray through all the passages you have to remove the mixture screw as well because the pilot jet and the mixer screw passage is connected so basically just spray out everything make sure it clean be very careful with the

float you don't want to damage that that is something that you mentioned in the instructions okay so now you've cleaned all the parts be careful when you take out

the fuel mixture screw that's the one at the bottom with the tab that you have to grind off there's a certain order that the parts have to go into mine just fell out

and I've googled this and there's a lot of inconsistency and how it needs to go in but it's pretty simple

it's when you take the screws first a spring on the screw then the little washer then the o-ring and then it goes into the carburetor

be careful not to damage the o-ring as you to screw it back in many ways when you take it out just be careful this part's going to come out and it has to be those three spring the washer and the owing

When you grind off the tab, I was a bit overzealous with the axle and I slipped just as I went through the tab that you have to grind off

And the whole thing fell on the floor and I broke off the tip

So I got a replacement that's better anyways because it's longer. You can now adjust it from the outside

So anyways, be careful. The problem then is I stopped there and I left it for a week while I waited for the mixture screw and I didn't put everything back together again

And then when I got the mixture, I put it back in and I went for a ride and it just ran horribly

What I forgot is to tighten the float-bull screws. And I know that stupid mistake that none of you will make, but the message here is don't stop a job halfway

Finish the job. Otherwise, stuff like that happens. Or put everything back together or leave everything apart

But don't stop halfway somewhere. You're going to forget what you did last time and make a mistake like I did there

Okay, now let's get geeky with the jet. sizes the stock jet sizes on the exos 650 L is a 50 pilot jet and a 152 main jet that's the size of the holes now the Davis mod calls for a 55 pilot jet so two sizes bigger and I think it's two sizes and then a 158 main jet and that's what I did so I ordered those and I stuck it in there the bike ran well but I had a few problems the one problem is the fuel consumption was

horrible. Now I don't ride carefully, I play around with the bikes, as you'll see in some of the other videos if you subscribe to this channel now, riding in the mud, doing donuts and crashing with the bike

So the fuel consumption was terrible. It wasn't great before. I think before with the stop jetting I measured it twice and it was 16.5 kilometers per litre thereabouts, but I was quite hard on the throttle and only playing around in the dirt here, not long distance highway riding

So that went down to 12.5 kilometers per litre. I mean that's terrible for a 650

single cylinder bike with that main jet. And the other problem is with the mixture

the fuel mixture you start off with two and a half turns out and then from there you can adjust it as in the description below and the instructions in the description below and I had to screw it all

the way in almost and the bike still wouldn't lower or the idle wouldn't drop so

that means the pilot jet was way too big way too rich too much fuel coming in so

then I read up again did some research on the jet sizes so one person said

know the Dave's mod is good from sea level that's where Dave's mod is supposed to be

correct from sea level to 6,000 feet that's what they said but I'm at 2,000 feet

and then I also found some places where they said for every 2,000 feet you rise in

altitude you need to go down one jet site on the pilot in the main

that makes sense because as you rise there's less oxygen so there's less air

coming in so the mixture will rich in by itself so then I went back and ordered

the size in between so one side down from Dave's mod so that's a 52 pilot and a 155 main jet that's what I've

got in there now and I've tested this with the fuel the first tank I got 17

kilometers per liter it's still not great I would love to see about 20 I know

other people get 20 kilometers per liter but it's much better the only caveat

this was completely unscientific I rode mostly on the highway well almost all of

the tank was on the highway but I do have to add that I fitted a 14 tooth sprocket in the front

The stock one was 15. So the first tank I mentioned was I think on the 15, then I switched

So I played around with different sprocket sizes as well. But at least from 12 and off yesterday to 17 today, the one was more playing around in the dirt, one was highway, but that big a difference can not only be about the riding style

I think the jets obviously made a big difference there. So anyways play around with the jet sizes do your research and don't just follow the instructions as is without being careful and planning ahead and chatting with other people that's done it before

So if you have any questions on the day's mod, my experience with doing it myself and then any rejetting

Please ask in the comments below if I can't answer you or just say so and someone else will hopefully pop in and it might give me ideas for future videos that I can research and then do that

cord I've got four different sized sprockets on its way I think a 13 14 15

15 and 16 tooth sprocket Fritzco sprot which I'm gonna test comprehensively and

compare more scientifically hopefully with an accelerometer on this channel so please subscribe now so you don't miss that and then if you have any questions or any

ideas that you want me to test while I test those four sprockets put that in

the comments below as well I'd love to hear from you and make those videos as helpful

possible and then please give a thumbs up to this video so more people can see this

and find this before they mess around with their jets on their bikes thank you for

joining me and I love the support and I'll see you next week cheers