Skorpion transmission snatch

[Berniecal]

I was out for a run today in 5degC and noticed rather more transmission snatch than I like, and I wonder what other Skorpion riders experience? I have the standard 15/39 sprockets and find anything less than 4000rpm in top produces unpleasant snatch, requiring a change-down. My chain is properly adjusted and lubed. Maybe the cush drive performs better at higher temperatures? I have only done a couple of hundred miles on the bike so far so don't yet have a good feel for the all-round performance. I'm very willing to rev the motor (5-7thousand is very satisfying:-) and definitely don't want to reopen the thumper versus modern-free-revving-single debate but would like to hear other experience on this topic.

[Old Dog]

My experience is that under 4K and you need to change gear. As per Bill's comments, trying to dig the bike out in a high gear on low revs is a non-runner. Ride it like a 2T, rev it and keep it revving. In the hills of Wales I rarely see top, then when things open up I put in top and off we go. Secondly I found that lubeing the chain is fine, but doesn't help in most cases. What I found does help is to clean the chain with some solvent (WD40) and also around the sprocket (paricularly the front) so that there is no build up of muck and the chain is dry. Then lube it with dry lube, I use Wurths, brilliant stuff. The combination of the two has made mine ride so much smoother.

If you want proof, I put my bike on the centrestand, rear wheel well clear of the ground, start it up, put in first and then let the revs drop and you can see for yourself the chain snatch. When you rev it the chain smooths out.

Good luck

Old Dog

[Mike G]

In my experience with a skorpion sport the rpm that transmission snatch becomes a problem is more dependent upon the carbureter setting accuracy than the chain. I have reset my previously badly set up carbureters and can now ride down to just below 3000 rpm before tranmission snatch sets in. The dual carb set up is very good at smoothing the running at low rpm when set up right. However if you crack open the throttle at low rpm it can come back, though the accelerator pump masks at lot of the problem with a richer mixture.

Mike

[Linegeist]

Sorry blokes, but I can't help thinking there's something wrong with a bike that snatches badly like you're describing ............... not to mention the possibility of excessive wear being caused to gears, sprockets and chains ........

Looked at in the cold light of day, a properly set up engine, even a big single like ours, with a decent flywheel (for storing power between firing strokes) should deliver 'relatively' uniform power pulses right down to just above stall point - assuming you're not trying to ride with a wide open throttle at 10MPH in top, natch' - in which case all bets are off and I'll sulk !!!

My bike'll happily run low down the rev band with no snatch - not that I ever give it a handful from low revs - I've learned from you lot that that loading the crank at low revs is the quick way to kill a big Yam single. Obviously she comes on song, like the good Lord intended, at around 3000rpm, but my Tour will tootle along at 1500/2000rpm in third, on just a whiff of throttle, and without any drama at all. I need to drop a gear if I want to accelerate anything like smartly of course but otherwise, she'll trickle along like this all day with no snatch. Perfect for gentle traffic work. She'll also idle at an indicated 950rpm (cable tacho) when warm, with a perfectly steady chuff-chuff beat of the classic big-single from the exhaust pipe.

Going back to the heady days of manual ignition adjustment from a lever on the handlbars, the kind of snatch you guys are describing was usually attributed to excessive ignition advance - along with loose/worn drivechains and/or worn cush drives. A common cause of chain-snatch was owners setting their drivechain tension on a tight spot of the chain run, so that when the bike was ridden, there was a lot more 'slop' in the loosest part of the the setup than was required. When the throttle was opened or closed, this slack gave rise to a noticeable jerk as the chain went from driving to braking, and it made low speed riding a pain in the neck as smooth power transitions were impossible to achieve.

Weak carburation at low revs also caused it, because cylinder combustion, instead of being even and smooth (called 'flame front propagation', would you believe ... Drop that into a conversation down the pub, and people think you actually know what you're talking about ), the fuel/air burn became ragged and harsh. On an ancient Triumph I owned, I cured this problem by raising the carb needle a notch, although the problem was also frequently caused by overtightened carb mating flanges allowing air into the inlet tract(s) on overrun. Exhaust 'banging' on overrun was a classic symptom (along with the 'snatchies' .........) I recently rebuilt a Honda GL that exhibited snatching on a regular basis - and that turned out to have a perished rubbur inlet stub.

So, Ipso facto ............ I'm wondering if there's a common underlying cause here -

[netguz]

Phew. I´ve been assuming that it was my lack of mechanical sympathy!

Mine ticks over (standard counter) at 11 to 1200 and is rideable from 2K up – yeah, it has to be nursed, but no lurching etc. From 3 it´s perfectly fine – although when REALLY hot it does seem to hesitate a fraction at 32 / 3300 – I´ve always assumed that that is when the ignition advances. Which it may be, but from Linegeists explanation – maybe I´m a touch lean. I´ve also just found a minor leak around the pipe / silencer joint – MOT due – should´ve checked earlier – but could be affecting things, possibly, maybe ....

I do agree with Bill J that it´s at it´s best above 4K, but I´m at my best flat on my back, glass of wine to hand, sun in the air, chatting with friends with some great music in the background; but somehow I still mange to go to work and earn a living!

[Linegeist]

............ I´m at my best flat on my back, glass of wine to hand, sun in the air, chatting with friends with some great music in the background; but somehow I still mange to go to work and earn a living!

I've just spent 3 years living in France doing that .............. I don't think I ever drove faster than 60kph. I don't 'arf want to go back ........

[Old Dog]

Don't start me about France - off in August for a few weeks...lovely!!

On the snatch side sounds to me as if we are in broad agreement.

[netguz]

Oh, France!

The area I know best is the Limousin.

take a peek, go on, y´now you want to, go on .....

http://www.tourismelimousin.com/fr/spip.php?rubrique21

I last went in´07, at one point the temperature got up to 40 deg C (100+ F), I had to get someone to turn the pages of my book, as I lazed by the pool, occasionally managing to stand up and then fall in.

The food, the people, the scenery, the life style ...............

Euro down, £ up, c´mon the Pound! (1.13)

[Linegeist]

<Drool> Nice area! We explored there one glorious long autumn weekend in '07 - beautiful!

We lived just outside Versailles in departement 78 - and a 25 minute RER train ride from Paris and haute civilisation. Nevertheless, we lived in a tiny village with nothing but a church, a boulangerie and a brasserie and countryside in every direction. There's room to breathe in France.

We found the people brilliant (once we'd learned to speak French, natch') and very helpful. The food was amazing, the wine laughably cheap and petrol was less expensive than the UK. Even the cops were more approachable. As for the roads - biker paradise!!!!

There's so much wrong with Britain right now, and spending time on the continent brings it into stark focus when you have to come back again .....

[netguz]

We´ve got to stop this!

I´ve just had a morning stroll around the quartier des artistes in Montmatre, then up to Sacre Coeur, lunch in the Jardin de Luxembourg, a stroll along the river, popping into the Ile de la Cite (not sure of the spelin) and then a good restaurant..

The next day I went to Chartres, the old bit around the Cathedral is lovely, as is the Cathedral.. Then on to Tours, I can´t find anything special about it, it just has a really nice ´feel´, and a fantastic Vietnamese, eat as much as you can, restaurant..

The next day, down to my friends place just outside Jumilhac le Grand, a week or three there, then Tours de Merle, over the Puy de something, Murat, what ......... oh, teatime ......... yeah, ........ OK.

[Old Dog]

if you lot don't bloody shut it I am leaving the forum...it is all getting to much..to emotional..the Loire with the Sunflowers out eating pate,cheese bread, a little wine... just shut it will you...I am close to tears..

[netguz]

Sorry Old Dog, but c´mon, wallow in those memories, dream the dream.

In terms of´Americanisation´, France is catching us up, which in netguz terms is sad.

Last weekend I was at CW motorcycles with a dodgy BMW waterpump. While the mechanics were having a look at it I got chatting to another customer. The topic was Scotland or Europe!

He suddenly ´went off on one´ - he just loves Scotland, esp the West coast, he got totally lost in his story, dragging me with him, and then suddenly the mechanic reappeared totally wrecking a very special moment.

Norman, if you´re around, AVON ¨Skin so Soft¨ - comments please.

Sometimes, memory and anticipation make life good.

Which is why I love touring, ferinstance, the Tours de Merle

http://guillaumebertrand.free.fr/voir/merle/

is one of Frances undiscovered secrets. I found it by chance and it´s in my ´must go back´ set of memories, but I´ve ´never done´ Provence.

Somewhere, eastish of Millau, is an ex-monastery built on the top of a very steep hill. It was closed! Can I even find it again? Will it be open?

This summer it´s either Europe, a mixture of ´must go back´ and ´never done´, or Scotland - ´never done´.

c´mon, wallow, be emotional, anticipate!

Streuth, I need a holiday!

[Linegeist]

All this talk of pate and wine (En terrace, naturellement) is just too much. Norman ought to remove this thread as dangerously addictive.

Bugger it! I've just booked an apartment for a week just outside Saint Germain en Laye (near where we used to live). Friends have been warned, dinner dates booked, and we're off next Wednesday (13th) to enjoy some civilisation - not to mention some sunshine, good food and a society where you're not photographed every 30 seconds.

Oh, the joys of semi-retirement!

[ajwebonly]

Wrong forum for Norman .... but I'm sure he wouldn't mind a travel section on his? Well as long as you take your bike with you.

[Linegeist]

Wrong forum for Norman .....

Well spotted! .............. erm, ........ 'course, I was just testing to see if anyone would notice I'd deliberately got the wrong forum .....

Clever clogs!!!