WD45 throttle response

Had my 57 WD45 gas out on a tractor ride on the weekend. Ran great considering it had not been used much in the last couple years.

One thing though, the throttle seems to be a bit lazy. You get a jump in engine speed at 1/3 throttle and another jump at 2/3 throttle. Hardly any change between each of those sections. I think it should be more uniform through the quadrant. Is there any adjustment for this?

Many thanks!

'49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '63 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080

HudCo wrote:

open up the main jet for a minet and throttle it up and cleat the crud out

Just had the carb cleaned in an ultrasonic cleaner 2 weeks ago. There would still be crud in it?

'49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '63 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080

A few thoughts. #1. Is the carb link rod properly "synch'd" ?? Engine off. Hand throttle wide open. Remove the cotter pin from the carburetor link rod/vertical governor arm behind the generator. Pull the link rod out of the hole. The vertical arm should not move to the rear. If it does move, make the link rod shorter (by bending down in the center) until it freely slides back into the hole. If it is 1/2 hole too short, that works even better and has no effect on engine HP. #2. Some WD40 or a drop of motor oil at each end of the carb link rod always is good. #3. This is important. If this problem has surfaced now after the carb was rebuilt, I'd be questioning the throttle shaft ease of movement . The throttle shaft has a special rubber seal on it. I have seen these special rubber seals (70226446) mismade (off and on for the last 30 or more years) causing too much drag on the ease of the throttle shaft to be able to move effortlessly. If there is any appreciable drag the governor just can't make it happen. Also, there is a brass retainer that is driven in after the seal that could be driven in too far swelling up the rubber seal. I NEVER use that retainer and install TWO of the 70226446 seals of the proper fit and have no dragging issues. A little WD40 on these upon assembly is really good. #4. If the throttle shaft area had repair bushings installed (for worn out holes) and they aren't done perfectly, this will cause the same problems....too much drag on the throttle shaft opening and closing. #5. The carb link rod cotter key at the carburetor must be trimmed off short and bent in such a fashion it cannot catch on anything !! another common mistake. #6. Maybe you are expecting too much. These mechanical gasoline governors are in no way as sensitive as a Roosa-Master diesel governor. The diesel governors seem to respond when you run over a road apple, where a gasoline governor just does nothing by comparison. #7. There is a rare chance that the governor fork inside the governor weights area isn't holding the cross shaft tight causing the vertical governor arm to change adjustment position. This is so rare I have only seen it a couple of times in 50 years, but it could be, so I have to mention it.

Edited by DrAllis - 26 Jul 2026 at 10:49am

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