Murray’s Carbs?
- Thread starter Iceman16
- Start date
None personally but I have never heard a bad thing about them.
Ditto. Except sometimes you have to rejet what Murray sent you but they are usually pretty good when you get them. And they are a carb you can buy yourself; you're ultimately paying for the 1into2 intakes.
Clemmons04
CB750 Member
I got a set and when I first got them they were great. He jets them extremely rich and gas mileage is horrible but when you turn the throttle it goes.
A few weeks ago when it started cooling off here in South Florida it started running pretty bad. I'm actually waiting on USPS today for some leaner jets. Even with the needle dropped all the way down the plugs run black and it tends to smoke a little black out the pipes because of how rich it is. I'm sure his engines he test them on are tip top but most of ours aren't.
For me I'm in South Florida heat and humidity and he tunes them from North Carolina so there will be a difference. They come well enough to run but like the other poster said you can buy these carbs yourself and I did. The only difference between his and how they come stock is the literally the main jet. He jets the main with a 240... Stock is 260. And he removes the air jet. Other than than no difference. Mikuni makes an endless amount of jets and needles that you could tune these to perfection which is surprising since he only swaps out the main. And if you question him he will without a doubt get defensive and tell you not to touch it and they are perfect. Far from it in my opinion.
My bike is an 81 750k stock. I've completely rebuilt it with genuine Honda parts. I had to wait weeks for parts to come from Japan for some items. My compression is 165 on all 4 and valves shimmed to .005, no excuses for a crappy running engine
. I get at most 100-115 miles out of a tank. That's almost 25mpg IF I run all 4.7 gallons but I fill up at 100mi.
Anyways hopefully new leaner jets will give me better fuel economy and solve my crappy running in the cooler weather. 90* and up runs great. As soon as it got 80* just pure crap. Overall good carb setup and fairly easy to tune. YMMV good luck
A few weeks ago when it started cooling off here in South Florida it started running pretty bad. I'm actually waiting on USPS today for some leaner jets. Even with the needle dropped all the way down the plugs run black and it tends to smoke a little black out the pipes because of how rich it is. I'm sure his engines he test them on are tip top but most of ours aren't.
For me I'm in South Florida heat and humidity and he tunes them from North Carolina so there will be a difference. They come well enough to run but like the other poster said you can buy these carbs yourself and I did. The only difference between his and how they come stock is the literally the main jet. He jets the main with a 240... Stock is 260. And he removes the air jet. Other than than no difference. Mikuni makes an endless amount of jets and needles that you could tune these to perfection which is surprising since he only swaps out the main. And if you question him he will without a doubt get defensive and tell you not to touch it and they are perfect. Far from it in my opinion.
My bike is an 81 750k stock. I've completely rebuilt it with genuine Honda parts. I had to wait weeks for parts to come from Japan for some items. My compression is 165 on all 4 and valves shimmed to .005, no excuses for a crappy running engine
. I get at most 100-115 miles out of a tank. That's almost 25mpg IF I run all 4.7 gallons but I fill up at 100mi. Anyways hopefully new leaner jets will give me better fuel economy and solve my crappy running in the cooler weather. 90* and up runs great. As soon as it got 80* just pure crap. Overall good carb setup and fairly easy to tune. YMMV good luck
Why does the 10° drop create poor performance? I would think the cooler air would be more dense and help against a rich condition.
I agree with Brett. If it is running rich then cooler air would help.
Clemmons04
CB750 Member
Idk... I just got those 2 steps down like you advised In my post a while ago. It's been a mystery to me. It was running great and then it wasn't. But remember I did put the slides in backwards so that was my fault. Either way it should have straitened out after putting the slides back but it hasn't. I've got 35 pilots and 240 mains. I just got my 32.5 and 30 pilots 230 and 220 mains in. Starting with 1 step down and if not leaning I'll swap in the 2 steps down. We'll see what happens.
I've heard from a few people that the Murray setup was overly rich for their bikes and as it cooled off it ran worse than it did in the summer. On the other hand I've heard from most people that even though overly rich it still runs quite well. Which I was in that crowd to begin with. Just not enough people out there with these to get good jet numbers from like say the XS650 bikes. They got the jet numbers down.... Then again a special 2 into 1 manifold isn't required to run the 34s either.
I've heard from a few people that the Murray setup was overly rich for their bikes and as it cooled off it ran worse than it did in the summer. On the other hand I've heard from most people that even though overly rich it still runs quite well. Which I was in that crowd to begin with. Just not enough people out there with these to get good jet numbers from like say the XS650 bikes. They got the jet numbers down.... Then again a special 2 into 1 manifold isn't required to run the 34s either.
Clemmons04
CB750 Member
I agree... 100% unless I'm missing something so obvious I'm not seeing it. Ive got another post about advance timing I'm working on. Ignition has been upgraded except the pickups and it idles great just above idle and loaded it breaks up and runs horrible. Brett advised 2 steps lean so that's where I'm at. Plugs say extremely rich so it makes sense to me.
I'm done with my issues here. The carb setup has fairly good reviews in my opinion and HAS been running great compared to the CV carbs. I would say that SpeedMotorCo is much more pleasant to deal with over Murray. Same setup. Different vendor
I'm done with my issues here. The carb setup has fairly good reviews in my opinion and HAS been running great compared to the CV carbs. I would say that SpeedMotorCo is much more pleasant to deal with over Murray. Same setup. Different vendor
If it idles well, don't change the pilot. Just focus on the main and then the needle. My two cents.
Coming off idle, those carbs use an accel pump, right? Have you checked that?
And by the way, this is something we all go thru with these bikes. The compression drives 70% of the bike's operation, and the rest is timing/ignition and carbs. I might have missed an item or two but you get it. Getting everything right is a time-consuming affair. Or better, a love-hate relationship.
Coming off idle, those carbs use an accel pump, right? Have you checked that?
And by the way, this is something we all go thru with these bikes. The compression drives 70% of the bike's operation, and the rest is timing/ignition and carbs. I might have missed an item or two but you get it. Getting everything right is a time-consuming affair. Or better, a love-hate relationship.
Clemmons04
CB750 Member
No... No accelerator pumps... It's a roll on off idle. You can snap it but most likely it will bog or stumble then rev. Basic as basic can be.
On a side note about the install use genuine Honda intake boots. The aftermarket are either to long or not thick enough. And with the genuine boots, the first time you tighten them make sure it's tight enough but not to tight... The hose clamps will cut the boots and split them after the heat cycles. And don't tighten the hose clamps while they are hot. It will also cut the boots. I know this first hand. The Honda boots are about $100-$130 on eBay but they are worth it. Cheapies are a fraction of the price... And for good reason
On a side note about the install use genuine Honda intake boots. The aftermarket are either to long or not thick enough. And with the genuine boots, the first time you tighten them make sure it's tight enough but not to tight... The hose clamps will cut the boots and split them after the heat cycles. And don't tighten the hose clamps while they are hot. It will also cut the boots. I know this first hand. The Honda boots are about $100-$130 on eBay but they are worth it. Cheapies are a fraction of the price... And for good reason
CatsuKatsu
CB750 New member
Speed Moto Co makes one for slightly cheaper for CB650s.
nighthawk mike
CB750 Member
Have considered using them myself as I have never heard a bad report and I like the setup. Although I'm one of those that likes something to be as it was made kind of people
I've read of a few people not getting their jetting right. But I'm not sure how much of that is Murray's jetting from the factory or the end user.
To be clear, i have heard far more good stories, which makes sense because Murray knows his sh*t.
To be clear, i have heard far more good stories, which makes sense because Murray knows his sh*t.
CatsuKatsu
CB750 New member
My problem is, I am getting 22-30 mpgs. I found that I am getting ~90 compression on all cylinders so that may change it on the rebuild. My other problem that a lot of people have been having is that when I give it an 1/8th or 1/4 slow throttle, the RPMs will stick around ~4k RPMs. I can try to snap the throttle to try to make it idle right but turning off the engine and turning it on is much easier.
The people with my problem have been using two springs to remedy it but makes the throttle stupidly stiff. They have verified my cable routing and have sent me an extra spring that I cut 3 loops off. Supposedly, I can revert back later and it will work but after 500 miles it still hasn't worked. This is supposed to be my long distance comfortable bike but hurts my calluses after 1 hours.
After my rebuild, I will probably go back to stock carbs and try some pod jetting setups that have been floating around in this forum.
The people with my problem have been using two springs to remedy it but makes the throttle stupidly stiff. They have verified my cable routing and have sent me an extra spring that I cut 3 loops off. Supposedly, I can revert back later and it will work but after 500 miles it still hasn't worked. This is supposed to be my long distance comfortable bike but hurts my calluses after 1 hours.
After my rebuild, I will probably go back to stock carbs and try some pod jetting setups that have been floating around in this forum.
metalgearunltd
CB750 Member
I have heard nothing but great things from Murray's Carbs. If there was an issue with a product, the customer service is next level with resolving issues and giving the buyers a great experience.
DennisAlan
CB750 Member
I have a set on my 82cb750 and love them! He will clean and tune them for you when time comes for free! I sent mine in and the turn around time was super fast and he even send me back a throttle cable because mine was bad. Any questions he'll give you his # and say just give me a call! Planning on buying another cb to build and murrys carbs will be going on it!
If I understand you right, one guy bought a quick turn throttle from Murray and it solved the same problem you have. The bike I'm rebuilding came with a set of Murrays. I sent them back to him for servicing and also told him I was 1300 feet higher than what it was jetted for. He rejetted them and also told me that I had the old style intakes and offered to sell me the new style at a cheap price. Very happy with his customer service.
I will admit i have no experience with SpeedMotorCo´s manifold but just looking at it it looks like trash to be honest, it is jsut three cut tubes welded together and that makes for very sharp corners in the manifold which will definetly cause a lot of turbulance, good for torque, but horrible for anything else, might be ok on some low revving bikes but on the higher revvong ones like the dohc i´m GUESSING that they wont be too fuel efficient or powerfull as stock.
laurnalhac
CB750 New member
Hello, I had the same issues with these carburetors in France on a 1983 Honda CB750 RC04.
The Mikuni VM34 Murrays setting was too rich for my location (south France), and I was disappointed with its performance.
After lots testings and hudge patience, the bike is now perfect with my following recipe:
- Pilot jet: #30 (#32.5 would be better)
- Air screw: 1+1/8
- Needle jet: 159-Q0
- Needle: 6DH2, clip in fourth position from the top
- Main jet: #220
- Air regulator jet: #2.0
I'm sharing this recipe to help the community.
For me, it solved all my stuck idle problems, bike no longer hesitates or stutters, and all the power is there.
The Mikuni VM34 Murrays setting was too rich for my location (south France), and I was disappointed with its performance.
After lots testings and hudge patience, the bike is now perfect with my following recipe:
- Pilot jet: #30 (#32.5 would be better)
- Air screw: 1+1/8
- Needle jet: 159-Q0
- Needle: 6DH2, clip in fourth position from the top
- Main jet: #220
- Air regulator jet: #2.0
I'm sharing this recipe to help the community.
For me, it solved all my stuck idle problems, bike no longer hesitates or stutters, and all the power is there.
