Yamaha SRX600 modding & rejetting?

[bacon]

Hi Guys,

I've got a 1985 srx400 with a srx600 engine ready to drop in. I'm looking to get a custom made exhaust 2 into 1 collector box made and a couple of pod filters to boot. I'm wondering if anybody has done this before on here and more importantly what to do about the carb rejetting.

Cheers,
Chris

[Twentypercent]

If you're using the original YDLS carbs, you should keep the airbox - they won't like pod filters at all.
No worries if you plan to swap the carbs out.

[bacon]

If you're using the original YDLS carbs, you should keep the airbox - they won't like pod filters at all.
No worries if you plan to swap the carbs out.

I see you're rocking an SRX too, glad to see I'm not the only one here . Have you done some mods?

[Grumph]

Hi Guys,

I've got a 1985 srx400 with a srx600 engine ready to drop in. I'm looking to get a custom made exhaust 2 into 1 collector box made and a couple of pod filters to boot. I'm wondering if anybody has done this before on here and more importantly what to do about the carb rejetting.

Cheers,
Chris

If i was doing an SRX600 again, I'd toss the OE carbs and either run a pair of decent slide carbs - Keihin CR's or a pair of flatslides - or just buy an inlet manifold off a 600 Big Bear quad and run a big single carb.

Trying to get the OE carbs to work right with a pipe, headwork and a cam can be frustration city as there are no alternative needles available....

[Twentypercent]

If i was doing an SRX600 again, I'd toss the OE carbs and either run a pair of decent slide carbs - Keihin CR's or a pair of flatslides - or just buy an inlet manifold off a 600 Big Bear quad and run a big single carb.

Trying to get the OE carbs to work right with a pipe, headwork and a cam can be frustration city as there are no alternative needles available....

+1 on the carbs.

Also, will you run into issues with chain/sprocket compatibility with that engine swap? I know the later SRX models aren't a simple swap from 400 to 600.

Mine's super standard, I got it to commute on, so I've never gotten around to any mods. The only thing that's not OE spec is the ghetto foam filter the PO has bodged up.

[bacon]

If i was doing an SRX600 again, I'd toss the OE carbs and either run a pair of decent slide carbs - Keihin CR's or a pair of flatslides - or just buy an inlet manifold off a 600 Big Bear quad and run a big single carb.

Trying to get the OE carbs to work right with a pipe, headwork and a cam can be frustration city as there are no alternative needles available....

Ah I had a funny feeling the OE carbs would need to be replaced. Might cost more than its worth I think, Unless I can find something like this second hand http://www.power-barn.com/servlet/the-743/Yamaha-SRX600S-fdsh-SC-Keihin-CR/Detail

the single carb idea might be a winner though, I'll have to ask around on the srx clubs I find online to see what they've done. Cheers for the tips mate, I sure do appreciate it

[bacon]

+1 on the carbs.

Also, will you run into issues with chain/sprocket compatibility with that engine swap? I know the later SRX models aren't a simple swap from 400 to 600.

Mine's super standard, I got it to commute on, so I've never gotten around to any mods. The only thing that's not OE spec is the ghetto foam filter the PO has bodged up.

I'm not sure what problems I'll run into with the chain and sprocket, but I guess I'll cross that bridge when I get to it. From what I've been told the engines drop right in without much work required. I've got the carbs to go with that 600 engine too, so I wont have to worry about that (if it was an issue). Also I've been trying to get a new air filter for my 400 as It's still got the original from 1985 with 45,000 or so on clock. Red Baron Quoted me $107! for a stock air filter!? I'm going to try order a hiflo or something from overseas for hopefully less than an arm and a leg

[bacon]

By the way any fellow srx owners with facebook may want to join this https://www.facebook.com/groups/121247204593918/ . Lots of useful information to be found

[Grumph]

Ah I had a funny feeling the OE carbs would need to be replaced. Might cost more than its worth I think, Unless I can find something like this second hand http://www.power-barn.com/servlet/the-743/Yamaha-SRX600S-fdsh-SC-Keihin-CR/Detail

the single carb idea might be a winner though, I'll have to ask around on the srx clubs I find online to see what they've done. Cheers for the tips mate, I sure do appreciate it

I was working for a yamaha dealer when the 600 big bear came out - i took one look and said, thank christ, that'll solve a lot of problems..

The single carb will be better everywhere except absolute top end. The POS std carbs will be the bane of your life....

[Twentypercent]

I'm not sure what problems I'll run into with the chain and sprocket, but I guess I'll cross that bridge when I get to it. From what I've been told the engines drop right in without much work required. I've got the carbs to go with that 600 engine too, so I wont have to worry about that (if it was an issue). Also I've been trying to get a new air filter for my 400 as It's still got the original from 1985 with 45,000 or so on clock. Red Baron Quoted me $107! for a stock air filter!? I'm going to try order a hiflo or something from overseas for hopefully less than an arm and a leg

If memory serves, an SRX400 runs 428 chain, and the 600 runs 520 chain. Which would be fine, except the output shafts are different, so front sprockets aren't compatible.
So you're probably looking at having to source a compatible rear sprocket to run the 520, but I don't know of anything that's an easy fit.
If you run into that problem and find a solution, I'd to be keen to hear what you do.
Pretty sure you can get a K&N filter to fit an 85 model airbox.

[bacon]

Hi Guys,

Been a while I know. I managed to score me a YFM600 manifold second hand for $50 or so and after a rummage through dads box-o-carburetors, I have come across the two following options. In the right corner we have a good ol Mikuni T38 flatside jetted for a hot Yamaha TT500 bored to a 550, In the left corner I have a Edelbrock QuickSilver 36-38 (weird oval) pumper carb (which I currently know nothing about, but I think its a kit for a xr650r). Any advice on which Carb to use and how to get it running right is greatly appreciated.

http://i.imgur.com/iktb36K.jpg?1

Cheers,
Chris

[avgas]

Stock carb is the worst carb on the planet. So Mikuni that badboy.

I tried many evenings to sort out the carb on my 400 - having sex with a pissed of hedgehog would have been less painful.

Made me sell the bike in the end.

[Grumph]

use the Mikuni - jets are readily available here and there's plenty of setup knowledge around.