throttle down, less power!

[oneshortplanck]

shes a 1978, 1850 HL

tootling along at 50mph, 2750rpm ish put foot down an inch to try and get to 60, all i get is a lot of suck from the carbs and feels like there may be less power,
another inch more and there is less of a sucking noise, but more grunt from the engine and exhaust, she pulls away ok, but not great.

is this flat spot common? Has anyone else got/had this problem?


only does this at 2500-3250 revs and when under load, i have taken the filter box off.
(I had a 1500TC before the 1850 and didnt get the sucking noise, she krept up to 60 withouut any need to kick down on the throttle.)

[Dollyboy]

put the filter box back on, preferably complete with filters.

10er says the problem just mysteriously goes away...

[Lewis]

As Dollyboy says basically! - Assuming you've removed the whole filter assembly, you get a lot more air in but the carbs can't compensate for this (they would need to add more fuel) - so you will suffer much poorer performance.

Put the box back on with it's filter - if the problem goes away, solved. If it lessens, then something's still amiss and you can go from there

[2F45T4U]

Points. My dolly is currently running no filters, performance isn't that affected, In fact I don't notice any difference to when it had them on. Points used to screw my 1850 up. Put your foot down, get more noise but not that much go. As it happend so gradually I only really used to know when I had to floor it to get passed Ford Ka's on the Mway!

[Lewis]

dolly is currently running no filters, performance isn't that affected

Wierd! Take the airbox of my old 1850, get to 3000RPM and it would pretty much do nothing bar make more noise!

(Not criticism, just an observation! Running on rampipes and filters was much the same, needles didn't supply enough fuel to match the airflow so after 4k it just collapsed from a 'performance' standpoint!)

Ignition system is probably worth looking at though.

Have to say my points gap never gave any grief in my 1850, RE closing up. Maybe I just was lucky!

[2F45T4U]

Yer i never had the problem with points until I changed to shitty Intermotor parts. OMG! The heels of them points are made out of cheese! I have about 3 sets of points that are useless due to the heels running out!

To be fair my dolly has the slightlier sportier needles and has a TR7 engine with HS6 carbs

[Lewis]

Intermotor parts

Yea I remember you saying about that. Poor aftermarket repro parts are bloody irritating!

[Nick C]

My dolly is currently running no filters

No wonder you get through engines so quickly!

There is a very good reason engines have air filters, never run one without! certainly not on the road - it only takes one small stone or something, and you've got one of the photos from the catastrophic mechanical failures thread!

[2F45T4U]

You obviosuly don't know how many engines I've been through and why. I've had a mere 4 different engines, because, 1850 would never make the power it should of, when it was close to being sorted... it started knocking! I fitted a TR7 engine that shot out TWO spark plugs! Fitted my next TR7 engine, Brilliant engine!!! Hauled my 1850 up to 110mph! Got my 1500 HL. engine started knocking after 55 miles of onwership, I only took it up to 75mph! Utter shite them engines!!! Now have that brilliant TR7 engine fitted with no air filters. Done 100mph for like 2 minutes the other day. Smokes a bit but for a £25 engine is pucker

[Jon Tilson]

You need one....they are there for good reason.

The TR7 HS6 setup uses the same air filter element as a sprint.

The 1850 often runs weak at higher revs...You can diagnose this by pulling the choke. If it goes better then its too weak...you need a richer needle or a TR7 manifold with HS6's.



Jonners

[Lewis]

You can diagnose this by pulling the choke

That's it! That's what Mark at Jigsaw told me to do and lo, on the motorway back, pulling it out led to much improved acceleration.

Visit to Leighton Buzzard Carb shop soon had it sorted with some better needles.....

[saitrix]

You can diagnose this by pulling the choke

That's it! That's what Mark at Jigsaw told me to do and lo, on the motorway back, pulling it out led to much improved acceleration.

Visit to Leighton Buzzard Carb shop soon had it sorted with some better needles.....

Nice easy way to see if there will be a gain to have richer needles!