East Coaster struggling in 4th

[djbgreeves]

I have been reading up on various tips & suggestions re East Coaster performance and would welcome some suggestions on my bike. The 4t was rebuilt by nametab and although it was running rich to start after adjusting the carb it seems to run pretty sweetly now. I guess it may be a bit tight from the rebuild although it revs nicely in the lower gears.

It goes well in the first 3 gears getting up to 50-55 in 3rd easily. But when I select 4th it seems to drop right out of the power band and stops building speed. If there's the slightest hill it needs dropping back to 3rd to hold 50-55. It's pleasant enough for bimbling along but another few mph would keep it away from the traffic. Any ideas on how to pep it up a bit?

[John Wakefield]

What size rear spocket have you fitted? When new the EC was fitted with a 52T rear sprocket. In my case I have fitted a 48T & its fine, but I do live in the flat lands of Cambridgeshire. The gearbox sprocket should be 18T.
You say the engine has recently been rebuilt so it will be tight & will need around 500 miles running in.

[greeves246]

performance

just a question are the points closing up ?

[djbgreeves]

Thanks for replies.

I think the points should be OK as it performs consistently well in lower gears as long as the revs are up. They have been modified to take modern points but are gapped OK. From what was explained when I bought the bike I think they'll be reliable. The bike almost seems over geared in 4th and it drops out of the (rather narrow) power band when I change up.

I'll take a look at the sprockets tomorrow and see what they are. I'm not sure about how to check the gear box one but if it is maxing out at about 55 in 3rd is that any guide?

I'm a bit heavier now than when I was 16 but 70 mph seemed easy enough back in the day & I'm hoping I can get it up towards that. I'm guessing at a total of about 300 miles from rebuild so maybe it will improve with more miles.

[John Wakefield]

To check the gearbox sprocket, lay the bike on its side (you may need to drain petrol tank) then make a chalk mark on one tooth & count the others. Its unlikely that the gearbox sprocket has been changed, more likely the rear.
Sounds overgeared to me, as on my bike I can change up at about 45 & it pulls away in top no problem, and its got a 52T sprocket. 55 in third would be almost max revs. It will need much more than 300 miles to really loosen up & for piston rings to bed in.
Having looked at a pic of your bike I note you have an Amal Concentic carb fitted. It should be a Villiers S25/6 (25mm bore) Not sure what size the Amal is but if its smaller than 25mm it may be restricting top end power. I have no info regarding jetting for the Amal but the Villiers S25/6 is as follows:
Taper needle: No 3 1/2 set to protrude 1.94 inches
Main jet: 180
Pilot jet: 35
Throttle slide: No 3 cutaway

[djbgreeves]

I have been checking out the bike this afternoon. The rear sprocket is a 52 tooth and the gear box is an 18 so that all looks standard. The bike has the correct S25/6 carb fitted. I understand the Amal was a temporary fitment & was swapped for the S26/6 soon after the pictures were taken - I can e mail you an up to date shot if you'd like one. I also bought the correct air filter from Viliers Suplies at the AGM and have fitted that too.

The carb had a No.4 slide fitted to overcome a rich running issue. I also have a No 3 so I have put that in this afternoon, resetting the needle as recommended. It sounds sweet enough. I am doing a charity ride out tomorrow, so I'll go on the Greeves to give it a good run & see how it goes.

[156trials]

The obvious thing to look at here (if not done already) is to decoke the complete exhaust system. Lots of people with 2T bikes insist on using far too much oil, and this quickly clogs the exhaust, and will really reduce the power of an engine, as well as limit RPM.

[John Wakefield]

The obvious thing to look at here (if not done already) is to decoke the complete exhaust system. Lots of people with 2T bikes insist on using far too much oil, and this quickly clogs the exhaust, and will really reduce the power of an engine, as well as limit RPM.

Good point there, but I think in this case the bike has had a full restoration with the previous owner & has been fitted with new silencers so they should be OK. I think it will loosen up with use, the top piston rings are chrome & need alot of bedding in.

[djbgreeves]

The day began in sunshine but it didn't last. Anyway one very wet charity ride completed and the bike didn't miss a beat. It's running much better with the no. 3 slide and re set needle and pulls up to around 60 fairly easily. It's probably still a bit short of where it should be but much better; and with the extra 5 mph certainly copes with A road traffic more comfortably.

[John Wakefield]

@dbjgreeves, glad to hear its going better, 60 is a bit fast for running in, I would keep it to below 50 for first 500 miles. I am sure it will loosen up & go much better as the miles go on.
Went out on my EC today & specially noted gear change speeds. In third 45mph is my normal change point & it accelerates cleanly away in top from that speed. Anything approaching 55 is 'ringing its neck' & does not add to accelleration in top. My bike also has higher gearing than yours (48T rear sprocket) so on yours with 52T sprocket I would have thought 40mph nearer the mark. My speedo incidentally is around 5mph fast at 30. I wonder therefore if your speedo is reading fast.
The correct speedo for EC is the Smiths grey faced dial with ref number SSM 2001/00 1600, & the drive is from the rear hub. Drive taken from gearbox outlet may not be at correct ratio & varies according to final drive ratio.